A judge on Monday ordered a Colorado woman to decrypt her laptop computer so prosecutors can use the files against her in a criminal case.

The defendant, accused of bank fraud, had unsuccessfully argued that being forced to do so violates the Fifth Amendment's protection against compelled self-incrimination.

"I conclude that the Fifth Amendment is not implicated by requiring production of the unencrypted contents of the Toshiba Satellite M305 laptop computer," Colorado U.S. District Judge Robert Blackburn ruled Monday. (.pdf)

The authorities seized the laptop from defendant Ramona Fricosu in 2010 with a court warrant while investigating financial fraud.

The case is being closely watched (.pdf) by civil rights groups, as the issue has never been squarely weighed in on by the Supreme Court.

Full disk encryption is an option built into the latest flavors of Windows, Mac OS and Linux, and well-designed encryption protocols used with a long passphrase can take decades to break, even with massive computing power.

The government had argued that there was no Fifth Amendment breach, and that it might "require significant resources and may harm the subject computer" if the authorities tried to crack the encryption.

Assistant U.S. Attorney Patricia Davies said in a court filing (.pdf) that if Judge Blackburn did not rule against the woman, that would amount to "a concession to her and potential criminals (be it in child exploitation, national security, terrorism, financial crimes or drug trafficking cases) that encrypting all inculpatory digital evidence will serve to defeat the efforts of law enforcement officers to obtain such evidence through judicially authorized search warrants, and thus make their prosecution impossible."

A factually similar dispute involving child pornography ended with a Vermont federal judge ordering the defendant to decrypt the hard drive of his laptop. While that case never reached the Supreme Court, it differed from the Fricosu matter because U.S. border agents already knew there was child porn on the computer because they saw it while the computer was running during a 2006 routine stop along the Canadian border.

The judge in the Colorado case said there was plenty of evidence – a jailhouse recording of the defendant – that the laptop might contain information the authorities were seeking.

The judge ordered Fricosu to surrender an unencrypted hard drive by Feb. 21. The judge added that the government is precluded "from using Ms. Fricosu's act of production of the unencrypted hard drive against her in any prosecution."