Law enforcement claims it is so hampered by security measures on electronic communications that it hurts efforts to track down criminals, and has called for tech companies to give them a so-called backdoor. The tech and security industries says there’s no way to do that without also giving hackers a foot in.

This debate, which was revived by recent terrorist attacks, continued to play out this week on Capitol Hill as Federal Bureau of Investigation Director James Comey said the agency has not been able to unlock the mobile phone of one of the attackers in the San Bernardino, Calif. shooting that killed 14 people.

On Wednesday, two congressmen introduced a bipartisan bill that would stop states from requiring tech companies to build back doors into electronic communications for law enforcement, calling it an issue that requires a national decision.

Encryption scrambles messages so only the parties involved (and sometimes the companies at hand) can read them. Law enforcement officials, like Comey, have said the technology helps criminals go “dark” and that security should be weakened so they can get a better view of text messages and other electronic communications.

There’s no evidence that recent terror attacks, like those in San Bernardino or Paris, could’ve been prevented if law enforcement had this kind of access.

​New York State Assemblyman Matthew Titone introduced a bill last month seeking to require that devices sold in the state are able to be unlocked by the manufacturer or operating system provider. A California lawmaker has introduced a similar bill.

The bill introduced in Congress Wednesday seeks to prohibit states from issuing such laws on what the sponsors of the legislation call a national issue.

​“Apple and Google can’t make a smartphone just for California and New York, and then a different one for Colorado and Wyoming,” says Rep. Ted Lieu (D-Calif.), who co-sponsored the bill.

“Whether one supports or opposes weakening encryption systems with a backdoor key, they can support this bill because all it says is that this issue needs to be decided at the federal level and that states cannot make this decision themselves,” Lieu says. The bill is co-sponsored by Rep. Blake Farenthold (R-Texas).

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Lieu majored in computer science at Stanford University. Like many in the technology and security industries, he is against the concept of mandating backdoors. “It’s technologically impossible to have a backdoor only for the FBI,” he says.

​”I​f our government can’t keep secret 20-something million security records, the most highly sensitive data the government has, no one should have any confidence our government can keep secret a backdoor encryption key,” Lieu added, referencing the Office of Personnel Management data breach disclosed last year.

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Law enforcement claims that terrorists are “going dark” by hiding their communications from investigations through encrypted technology are overstated, researchers at Harvard University’s Berkman Center for Internet & Society concluded in a report released Feb. 1. Law enforcement has a greater range of surveillance options thanks to modern technology, the report said, and “communications in the future will neither be eclipsed into darkness nor illuminated without shadow.” The Internet of Things, a name applied to objects connected to the Internet, provide an opportunity for law enforcement to watch suspects, as does metadata. (Metadata is information such as the header of an email that says who is sending and receiving a message, and location data from a cell phone.)