Killed by Code: Software Transparency in Implantable Medical Devices

Karen Sandler

Lysandra Ohrstrom

Laura Moy

Robert McVay

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Copyright © 2010, Software Freedom Law Center. Verbatim copying of this document is permitted in any medium; this notice must be preserved on all copies.

I Abstract

Software is an integral component of a range of devices that perform critical, lifesaving functions and basic daily tasks. As patients grow more reliant on computerized devices, the dependability of software is a life-or-death issue. The need to address software vulnerability is especially pressing for Implantable Medical Devices (IMDs), which are commonly used by millions of patients to treat chronic heart conditions, epilepsy, diabetes, obesity, and even depression.

The software on these devices performs life-sustaining functions such as cardiac pacing and defibrillation, drug delivery, and insulin administration. It is also responsible for monitoring, recording and storing private patient information, communicating wirelessly with other computers, and responding to changes in doctors’ orders.

The Food and Drug Administration (FDA) is responsible for evaluating the risks of new devices and monitoring the safety and efficacy of those currently on market. However, the agency is unlikely to scrutinize the software operating on devices during any phase of the regulatory process unless a model that has already been surgically implanted repeatedly malfunctions or is recalled.

The FDA has issued 23 recalls of defective devices during the first half of 2010, all of which are categorized as “Class I,” meaning there is “reasonable probability that use of these products will cause serious adverse health consequences or death.” At least six of the recalls were likely caused by software defects.1 Physio-Control, Inc., a wholly owned subsidiary of Medtronic and the manufacturer of one defibrillator that was probably recalled due to software-related failures, admitted in a press release that it had received reports of similar failures from patients “over the eight year life of the product,” including one “unconfirmed adverse patient event.”2

Despite the crucial importance of these devices and the absence of comprehensive federal oversight, medical device software is considered the exclusive property of its manufacturers, meaning neither patients nor their doctors are permitted to access their IMD’s source code or test its security.3

In 2008, the Supreme Court of the United States’ ruling in Riegel v. Medtronic, Inc. made people with IMDs even more vulnerable to negligence on the part of device manufacturers.4 Following a wave of high-profile recalls of defective IMDs in 2005, the Court’s decision prohibited patients harmed by defects in FDA-approved devices from seeking damages against manufacturers in state court and eliminated the only consumer safeguard protecting patients from potentially fatal IMD malfunctions: product liability lawsuits. Prevented from recovering compensation from IMD-manufacturers for injuries, lost wages, or health expenses in the wake of device failures, people with chronic medical conditions are now faced with a stark choice: trust manufacturers entirely or risk their lives by opting against life-saving treatment.

We at the Software Freedom Law Center (SFLC) propose an unexplored solution to the software liability issues that are increasingly pressing as the population of IMD-users grows--requiring medical device manufacturers to make IMD source-code publicly auditable. As a non-profit legal services organization for Free and Open Source (FOSS) software developers, part of the SFLC’s mission is to promote the use of open, auditable source code5 in all computerized technology. This paper demonstrates why increased transparency in the field of medical device software is in the public’s interest. It unifies various research into the privacy and security risks of medical device software and the benefits of published systems over closed, proprietary alternatives. Our intention is to demonstrate that auditable medical device software would mitigate the privacy and security risks in IMDs by reducing the occurrence of source code bugs and the potential for malicious device hacking in the long-term. Although there is no way to eliminate software vulnerabilities entirely, this paper demonstrates that free and open source medical device software would improve the safety of patients with IMDs, increase the accountability of device manufacturers, and address some of the legal and regulatory constraints of the current regime.

We focus specifically on the security and privacy risks of implantable medical devices, specifically pacemakers and implantable cardioverter defibrillators, but they are a microcosm of the wider software liability issues which must be addressed as we become more dependent on embedded systems and devices. The broader objective of our research is to debunk the “security through obscurity” misconception by showing that vulnerabilities are spotted and fixed faster in FOSS programs compared to proprietary alternatives. The argument for public access to source code of IMDs can, and should be, extended to all the software people interact with everyday. The well-documented recent incidents of software malfunctions in voting booths, cars, commercial airlines, and financial markets are just the beginning of a problem that can only be addressed by requiring the use of open, auditable source code in safety-critical computerized devices.6

In section one, we give an overview of research related to potentially fatal software vulnerabilities in IMDs and cases of confirmed device failures linked to source code vulnerabilities. In section two, we summarize research on the security benefits of FOSS compared to closed-source, proprietary programs. In section three, we assess the technical and legal limitations of the existing medical device review process and evaluate the FDA’s capacity to assess software security. We conclude with our recommendations on how to promote the use of FOSS in IMDs. The research suggests that the occurrence of privacy and security breaches linked to software vulnerabilities is likely to increase in the future as embedded devices become more common.

II Software Vulnerabilities in IMDs

A variety of wirelessly reprogrammable IMDs are surgically implanted directly into the body to detect and treat chronic health conditions. For example, an implantable cardioverter defibrillator, roughly the size of a small mobile phone, connects to a patient’s heart, monitors rhythm, and delivers an electric shock when it detects abnormal patterns. Once an IMD has been implanted, health care practitioners extract data, such as electrocardiogram readings, and modify device settings remotely, without invasive surgery. New generation ICDs can be contacted and reprogrammed via wireless radio signals using an external device called a “programmer.”

In 2008, approximately 350,000 pacemakers and 140,000 ICDs were implanted in the United States, according to a forecast on the implantable medical device market published earlier this year.7 Nation-wide demand for all IMDs is projected to increase 8.3 percent annually to $48 billion by 2014, the report says, as “improvements in safety and performance properties …enable ICDs to recapture growth opportunities lost over the past year to product recall.”8 Cardiac implants in the U.S. will increase 7.3 percent annually, the article predicts, to $16.7 billion in 2014, and pacing devices will remain the top-selling group in this category.9

Though the surge in IMD treatment over the past decade has had undeniable health benefits, device failures have also had fatal consequences. From 1997 to 2003, an estimated 400,000 to 450,000 ICDs were implanted world-wide and the majority of the procedures took place in the United States. At least 212 deaths from device failures in five different brands of ICD occurred during this period, according to a study of the adverse events reported to the FDA conducted by cardiologists from the Minneapolis Heart Institute Foundation.10

Research indicates that as IMD usage grows, the frequency of potentially fatal software glitches, accidental device malfunctions, and the possibility of malicious attacks will grow. While there has yet to be a documented incident in which the source code of a medical device was breached for malicious purposes, a 2008-study led by software engineer and security expert Kevin Fu proved that it is possible to interfere with an ICD that had passed the FDA’s premarket approval process and been implanted in hundreds of thousands of patients. A team of researchers from three universities partially reverse-engineered the communications protocol of a 2003-model ICD and launched several radio-based software attacks from a short distance. Using low-cost, commercially available equipment to bypass the device programmer, the researchers were able to extract private data stored inside the ICD such as patients’ vital signs and medical history; “eavesdrop” on wireless communication with the device programmer; reprogram the therapy settings that detect and treat abnormal heart rhythms; and keep the device in “awake” mode in order to deplete its battery, which can only be replaced with invasive surgery.

In one experimental attack conducted in the study, researchers were able to first disable the ICD to prevent it from delivering a life-saving shock and then direct the same device to deliver multiple shocks averaging 137.7 volts that would induce ventricular fibrillation in a patient. The study concluded that there were no “technological mechanisms in place to ensure that programmers can only be operated by authorized personnel.” Fu’s findings show that almost anyone could use store-bought tools to build a device that could “be easily miniaturized to the size of an iPhone and carried through a crowded mall or subway, sending its heart-attack command to random victims.”11

The vulnerabilities Fu’s lab exploited are the result of the very same features that enable the ICD to save lives. The model breached in the experiment was designed to immediately respond to reprogramming instructions from health-care practitioners, but is not equipped to distinguish whether treatment requests originate from a doctor or an adversary. An earlier paper co-authored by Fu proposed a solution to the communication-security paradox. The paper recommends the development of a wearable “cloaker” for IMD-patients that would prevent anyone but pre-specified, authorized commercial programmers to interact with the device. In an emergency situation, a doctor with a previously unauthorized commercial programmer would be able to enable emergency access to the IMD by physically removing the cloaker from the patient.12

Though the adversarial conditions demonstrated in Fu’s studies were hypothetical, two early incidents of malicious hacking underscore the need to address the threat software liabilities pose to the security of IMDs. In November 2007, a group of attackers infiltrated the Coping with Epilepsy website and planted flashing computer animations that triggered migraine headaches and seizures in photosensitive site visitors.13 A year later, malicious hackers mounted a similar attack on the Epilepsy Foundation website.14

Ample evidence of software vulnerabilities in other common IMD treatments also indicates that the worst-case scenario envisioned by Fu’s research is not unfounded. From 1983 to 1997 there were 2,792 quality problems that resulted in recalls of medical devices, 383 of which were related to computer software, according to a 2001 study analyzing FDA reports of the medical devices that were voluntarily recalled by manufacturers over a 15-year period.15 Cardiology devices accounted for 21 percent of the IMDs that were recalled. Authors Dolores R. Wallace and D. Richard Kuhn discovered that 98 percent of the software failures they analyzed would have been detected through basic scientific testing methods. While none of the failures they researched caused serious personal injury or death, the paper notes that there was not enough information to determine the potential health consequences had the IMDs remained in service.

Nearly 30 percent of the software-related recalls investigated in the report occurred between 1994 and 1996. “One possibility for this higher percentage in later years may be the rapid increase of software in medical devices. The amount of software in general consumer products is doubling every two to three years,” the report said.

As more individual IMDs are designed to automatically communicate wirelessly with physician’s offices, hospitals, and manufacturers, routine tasks like reprogramming, data extraction, and software updates may spur even more accidental software glitches that could compromise the security of IMDs.

The FDA launched an “Infusion Pump Improvement Initiative” in April 2010, after receiving thousands of reports of problems associated with the use of infusion pumps that deliver fluids such as insulin and chemotherapy medication to patients electronically and mechanically.16 Between 2005 and 2009, the FDA received approximately 56,000 reports of adverse events related to infusion pumps, including numerous cases of injury and death. The agency analyzed the reports it received during the period in a white paper published in the spring of 2010 and found that the most common types of problems reported were associated with software defects or malfunctions, user interface issues, and mechanical or electrical failures. (The FDA said most of the pumps covered in the report are operated by a trained user, who programs the rate and duration of fluid delivery through a built-in software interface). During the period, 87 infusion pumps were recalled due to safety concerns, 14 of which were characterized as “Class I” – situations in which there is a reasonable probability that use of the recalled device will cause serious adverse health consequences or death. Software defects lead to over-and-under infusion and caused pre-programmed alarms on pumps to fail in emergencies or activate in absence of a problem. In one instance a “key bounce” caused an infusion pump to occasionally register one keystroke (e.g., a single zero, “0”) as multiple keystrokes (e.g., a double zero, “00”), causing an inappropriate dosage to be delivered to a patient. Though the report does not apply to implantable infusion pumps, it demonstrates the prevalence of software-related malfunctions in medical device software and the flexibility of the FDA’s pre-market approval process.

In order to facilitate the early detection and correction of any design defects, the FDA has begun offering manufacturers “the option of submitting the software code used in their infusion pumps for analysis by agency experts prior to premarket review of new or modified devices.” It is also working with third-party researchers to develop “an open-source software safety model and reference specifications that infusion pump manufacturers can use or adapt to verify the software in their devices.”

Though the voluntary initiative appears to be an endorsement of the safety benefits of FOSS and a step in the right direction, it does not address the overall problem of software insecurity since it is not mandatory.

III Why Free Software is More Secure

“Continuous and broad peer-review, enabled by publicly available source code, improves software reliability and security through the identification and elimination of defects that might otherwise go unrecognized by the core development team. Conversely, where source code is hidden from the public, attackers can attack the software anyway …. Hiding source code does inhibit the ability of third parties to respond to vulnerabilities (because changing software is more difficult without the source code), but this is obviously not a security advantage. In general, ‘Security by Obscurity’ is widely denigrated.” — Department of Defense (DoD) FAQ’s response to question: “Doesn’t Hiding Source Code Automatically Make Software More Secure?”17

The DoD indicates that FOSS has been central to its Information Technology (IT) operations since the mid-1990’s, and, according to some estimates, one-third to one-half of the software currently used by the agency is open source.18 The U.S. Office of Management and Budget issued a memorandum in 2004, which recommends that all federal agencies use the same procurement procedures for FOSS as they would for proprietary software.19 Other public sector agencies, such as the U.S. Navy, the Federal Aviation Administration, the U.S. Census Bureau and the U.S. Patent and Trademark Office have been identified as recognizing the security benefits of publicly auditable source code.20

To understand why free and open source software has become a common component in the IT systems of so many businesses and organizations that perform life-critical or mission-critical functions, one must first accept that software bugs are a fact of life. The Software Engineering Institute estimates that an experienced software engineer produces approximately one defect for every 100 lines of code.21 Based on this estimate, even if most of the bugs in a modest, one million-line code base are fixed over the course of a typical program life cycle, approximately 1,000 bugs would remain.

In its first “State of Software Security” report released in March 2010, the private software security analysis firm Veracode reviewed the source code of 1,591 software applications voluntarily submitted by commercial vendors, businesses, and government agencies.22 Regardless of program origins, Veracode found that 58 percent of all software submitted for review did not meet the security assessment criteria the report established.23 Based on its findings, Veracode concluded that “most software is indeed very insecure …[and] more than half of the software deployed in enterprises today is potentially susceptible to an application layer attack similar to that used in the recent …Google security breaches.”24

Though open source applications had almost as many source code vulnerabilities upon first submission as proprietary programs, researchers found that they contained fewer potential backdoors than commercial or outsourced software and that open source project teams remediated security vulnerabilities within an average of 36 days of the first submission, compared to 48 days for internally developed applications and 82 days for commercial applications.25 Not only were bugs patched the fastest in open source programs, but the quality of remediation was also higher than commercial programs.26

Veracode’s study confirms the research and anecdotal evidence into the security benefits of open source software published over the past decade. According to the web-security analysis site SecurityPortal, vulnerabilities took an average of 11.2 days to be spotted in Red Hat/Linux systems with a standard deviation of 17.5 compared to an average of 16.1 days with a standard deviation of 27.7 in Microsoft programs.27

Sun Microsystems’ COO Bill Vass summed up the most common case for FOSS in a blog post published in April 2009: “By making the code open source, nothing can be hidden in the code,” Vass wrote. “If the Trojan Horse was made of glass, would the Trojans have rolled it into their city? NO.”28

Vass’ logic is backed up by numerous research papers and academic studies that have debunked the myth of security through obscurity and advanced the “more eyes, fewer bugs” thesis. Though it might seem counterintuitive, making source code publicly available for users, security analysts, and even potential adversaries does not make systems more vulnerable to attack in the long-run. To the contrary, keeping source code under lock-and-key is more likely to hamstring “defenders” by preventing them from finding and patching bugs that could be exploited by potential attackers to gain entry into a given code base, whether or not access is restricted by the supplier.29 “In a world of rapid communications among attackers where exploits are spread on the Internet, a vulnerability known to one attacker is rapidly learned by others,” reads a 2006 article comparing open source and proprietary software use in government systems.30 “For Open Source, the next assumption is that disclosure of a flaw will prompt other programmers to improve the design of defenses. In addition, disclosure will prompt many third parties — all of those using the software or the system — to install patches or otherwise protect themselves against the newly announced vulnerability. In sum, disclosure does not help attackers much but is highly valuable to the defenders who create new code and install it.”

Academia and internet security professionals appear to have reached a consensus that open, auditable source code gives users the ability to independently assess the exposure of a system and the risks associated with using it; enables bugs to be patched more easily and quickly; and removes dependence on a single party, forcing software suppliers and developers to spend more effort on the quality of their code, as authors Jaap-Henk Hoepman and Bart Jacobs also conclude in their 2007 article, Increased Security Through Open Source.31

By contrast, vulnerabilities often go unnoticed, unannounced, and unfixed in closed source programs because the vendor, rather than users who have a higher stake in maintaining the quality of software, is the only party allowed to evaluate the security of the code base.32 Some studies have argued that commercial software suppliers have less of an incentive to fix defects after a program is initially released so users do not become aware of vulnerabilities until after they have caused a problem. “Once the initial version of [a proprietary software product] has saturated its market, the producer’s interest tends to shift to generating upgrades …Security is difficult to market in this process because, although features are visible, security functions tend to be invisible during normal operations and only visible when security trouble occurs.”33

The consequences of manufacturers’ failure to disclose malfunctions to patients and physicians have proven fatal in the past. In 2005, a 21-year-old man died from cardiac arrest after the ICD he wore short-circuited and failed to deliver a life-saving shock. The fatal incident prompted Guidant, the manufacturer of the flawed ICD, to recall four different device models they sold. In total 70,000 Guidant ICDs were recalled in one of the biggest regulatory actions of the past 25 years.34

Guidant came under intense public scrutiny when the patient’s physician Dr. Robert Hauser discovered that the company first observed the flaw that caused his patient’s device to malfunction in 2002, and even went so far as to implement manufacturing changes to correct it, but failed to disclose it to the public or health-care industry.

The body of research analyzed for this paper points to the same conclusion: security is not achieved through obscurity and closed source programs force users to forfeit their ability to evaluate and improve a system’s security. Though there is lingering debate over the degree to which end-users contribute to the maintenance of FOSS programs and how to ensure the quality of the patches submitted, most of the evidence supports our paper’s central assumption that auditable, peer-reviewed software is comparatively more secure than proprietary programs.

Programs have different standards to ensure the quality of the patches submitted to open source programs, but even the most open, transparent systems have established methods of quality control. Well-established open source software, such as the kind favored by the DoD and the other agencies mentioned above, cannot be infiltrated by “just anyone.” To protect the code base from potential adversaries and malicious patch submissions, large open source systems have a “trusted repository” that only certain, “trusted,” developers can directly modify. As an additional safeguard, the source code is publicly released, meaning not only are there more people policing it for defects, but more copies of each version of the software exist making it easier to compare new code.

IV The FDA Review Process and Legal Obstacles to Device Manufacturer Accountability

“Implanted medical devices have enriched and extended the lives of countless people, but device malfunctions and software glitches have become modern ‘diseases’ that will continue to occur. The failure of manufacturers and the FDA to provide the public with timely, critical information about device performance, malfunctions, and ’fixes’ enables potentially defective devices to reach unwary consumers.” — Capitol Hill Hearing Testimony of William H. Maisel, Director of Beth Israel Deaconess Medical Center, May 12, 2009.

The FDA’s Center for Devices and Radiological Health (CDRH) is responsible for regulating medical devices, but since the Medical Device Modernization Act (MDMA) was passed in 1997 the agency has increasingly ceded control over the pre-market evaluation and post-market surveillance of IMDs to their manufacturers.35 While the agency has been making strides towards the MDMA’s stated objective of streamlining the device approval process, the expedient regulatory process appears to have come at the expense of the CDRH’s broader mandate to “protect the public health in the fields of medical devices” by developing and implementing programs “intended to assure the safety, effectiveness, and proper labeling of medical devices.”36

Since the MDMA was passed, the FDA has largely deferred these responsibilities to the companies that sell these devices.37 The legislation effectively allowed the businesses selling critical devices to establish their own set of pre-market safety evaluation standards and determine the testing conducted during the review process. Manufacturers also maintain a large degree of discretion over post-market IMD surveillance. Though IMD-manufacturers are obligated to inform the FDA if they alert physicians to a product defect or if the device is recalled, they determine whether a particular defect constitutes a public safety risk.

“Manufacturers should use good judgment when developing their quality system and apply those sections of the QS regulation that are applicable to their specific products and operations,” reads section 21 of Quality Standards regulation outlined on the FDA’s website. “Operating within this flexibility, it is the responsibility of each manufacturer to establish requirements for each type or family of devices that will result in devices that are safe and effective, and to establish methods and procedures to design, produce, distribute, etc. devices that meet the quality system requirements. The responsibility for meeting these requirements and for having objective evidence of meeting these requirements may not be delegated even though the actual work may be delegated.”

By implementing guidelines such as these, the FDA has refocused regulation from developing and implementing programs in the field of medical devices that protect the public health to auditing manufacturers’ compliance with their own standards.

“To the FDA, you are the experts in your device and your quality programs,” Jeff Geisler wrote in a 2010 book chapter, Software for Medical Systems.38 “Writing down the procedures is necessary — it is assumed that you know best what the procedures should be — but it is essential that you comply with your written procedures.”

The elastic regulatory standards are a product of the 1976 amendment to the Food, Drug, and Cosmetics Act.39The Amendment established three different device classes and outlined broad pre-market requirements that each category of IMD must meet depending on the risk it poses to a patient. Class I devices, whose failure would have no adverse health consequences, are not subject to a pre-market approval process. Class III devices that “support or sustain human life, are of substantial importance in preventing impairment of human health, or which present a potential, unreasonable risk of illness or injury,” such as IMDs, are subject to the most stringent FDA review process, Premarket Approval (PMA).40

By the FDA’s own admission, the original legislation did not account for technological complexity of IMDs, but neither has subsequent regulation.41

In 2002, an amendment to the MDMA was passed that was intended to help the FDA “focus its limited inspection resources on higher-risk inspections and give medical device firms that operate in global markets an opportunity to more efficiently schedule multiple inspections,” the agency’s website reads.42

The legislation further eroded the CDRH’s control over pre-market approval data, along with the FDA’s capacity to respond to rapid changes in medical treatment and the introduction of increasingly complex devices for a broader range of diseases. The new provisions allowed manufacturers to pay certain FDA-accredited inspectors to conduct reviews during the PMA process in lieu of government regulators. It did not outline specific software review procedures for the agency to conduct or precise requirements that medical device manufacturers must meet before introducing a new product. “The regulation …provides some guidance [on how to ensure the reliability of medical device software],” Joe Bremner wrote of the FDA’s guidance on software validation.43 “Written in broad terms, it can apply to all medical device manufacturers. However, while it identifies problems to be solved or an end point to be achieved, it does not specify how to do so to meet the intent of the regulatory requirement.”

The death of 21-year-old Joshua Oukrop in 2005 due to the failure of a Guidant device has increased calls for regulatory reform at the FDA.44 In a paper published shortly after Oukrop’s death, his physician, Dr. Hauser concluded that the FDA’s post-market ICD device surveillance system is broken.45

After returning the failed Prizm 2 DR pacemaker to Guidant, Dr. Hauser learned that the company had known the model was prone to the same defect that killed Oukrop for at least three years. Since 2002, Guidant received 25 different reports of failures in the Prizm model, three of which required rescue defibrillation. Though the company was sufficiently concerned about the problem to make manufacturing changes, Guidant continued to sell earlier models and failed to make patients and physicians aware that the Prizm was prone to electronic defects. They claimed that disclosing the defect was inadvisable because the risk of infection during de-implantation surgery posed a greater threat to public safety than device failure. “Guidant’s statistical argument ignored the basic tenet that patients have a fundamental right to be fully informed when they are exposed to the risk of death no matter how low that risk may be perceived,” Dr. Hauser argued. “Furthermore, by withholding vital information, Guidant had in effect assumed the primary role of managing high-risk patients, a responsibility that belongs to physicians. The prognosis of our young, otherwise healthy patient for a long, productive life was favorable if sudden death could have been prevented.”

The FDA was also guilty of violating the principle of informed consent. In 2004, Guidant had reported two different adverse events to the FDA that described the same defect in the Prizm 2 DR models, but the agency also withheld the information from the public. “The present experience suggests that the FDA is currently unable to satisfy its legal responsibility to monitor the safety of market released medical devices like the Prizm 2 DR,” he wrote, referring to the device whose failure resulted in his patient’s death. “The explanation for the FDA’s inaction is unknown, but it may be that the agency was not prepared for the extraordinary upsurge in ICD technology and the extraordinary growth in the number of implantations that has occurred in the past five years.”

While the Guidant recalls prompted increased scrutiny on the FDA’s medical device review process, it remains difficult to gauge the precise process of regulating IMD software or the public health risk posed by source code bugs since neither doctors, nor IMD users, are permitted to access it. Nonetheless, the information that does exist suggests that the pre-market approval process alone is not a sufficient consumer safeguard since medical devices are less likely than drugs to have demonstrated clinical safety before they are marketed.46

An article published in the Journal of the American Medical Association (JAMA) studied the safety and effectiveness data in every PMA application the FDA reviewed from January 2000 to December 2007 and concluded that “premarket approval of cardiovascular devices by the FDA is often based on studies that lack strength and may be prone to bias.”47 Of the 78 high-risk device approvals analyzed in the paper, 51 were based on a single study.48

The JAMA study noted that the need to address the inadequacies of the FDA’s device regulation process has become particularly urgent since the Supreme Court changed the landscape of medical liability law with its ruling in Riegel v. Medtronic in February 2008. The Court held that the plaintiff Charles Riegel could not seek damages in state court from the manufacturer of a catheter that exploded in his leg during an angioplasty. “Riegel v. Medtronic means that FDA approval of a device preempts consumers from suing because of problems with the safety or effectiveness of the device, making this approval a vital consumer protection safeguard.”49

Since the FDA is a federal agency, its authority supersedes state law. Based on the concept of preemption, the Supreme Court held that damages actions permitted under state tort law could not be filed against device manufacturers deemed to be in compliance with the FDA, even in the event of gross negligence. The decision eroded one of the last legal recourses to protect consumers and hold IMD manufacturers accountable for catastrophic, failure of an IMD. Not only are the millions of people who rely on IMD’s for their most life-sustaining bodily functions more vulnerable to software malfunctions than ever before, but they have little choice but to trust its manufacturers.

“It is clear that medical device manufacturers have responsibilities that extend far beyond FDA approval and that many companies have failed to meet their obligations,” William H. Maisel said in recent congressional testimony on the Medical Device Reform bill.50 “Yet, the U.S. Supreme Court ruled in their February 2008 decision, Riegel v. Medtronic, that manufacturers could not be sued under state law by patients harmed by product defects from FDA-approved medical devices …. [C]onsumers are unable to seek compensation from manufacturers for their injuries, lost wages, or health expenses. Most importantly, the Riegel decision eliminates an important consumer safeguard — the threat of manufacturer liability — and will lead to less safe medical devices and an increased number of patient injuries.”

In light of our research and the existing legal and regulatory limitations that prevent IMD users from holding medical device manufacturers accountable for critical software vulnerabilities, auditable source code is critical to minimize the harm caused by inevitable medical device software bugs.

V Conclusion

The Supreme Court’s decision in favor of Medtronic in 2008, increasingly flexible regulation of medical device software on the part of the FDA, and a spike in the level and scope of IMD usage over the past decade suggest a software liability nightmare on the horizon. We urge the FDA to introduce more stringent, mandatory standards to protect IMD-wearers from the potential adverse consequences of software malfunctions discussed in this paper. Specifically, we call on the FDA to require manufacturers of life-critical IMDs to publish the source code of medical device software so the public and regulators can examine and evaluate it. At the very least, we urge the FDA to establish a repository of medical device software running on implanted IMDs in order to ensure continued access to source code in the event of a catastrophic failure, such as the bankruptcy of a device manufacturer. While we hope regulators will require that the software of all medical devices, regardless of risk, be auditable, it is particularly urgent that these standards be included in the pre-market approval process of Class III IMDs. We hope this paper will also prompt IMD users, their physicians, and the public to demand greater transparency in the field of medical device software.