Drunk drivers granted access to breathalyser source code

Judges rule that source code is 'material to the defence'

A panel of judges in the Florida county of Sarasota has granted a request by a group of over 150 citizens accused of drink-driving to view the source code of the breathalyser that was used to determine their breath alcohol levels.

Attorneys for the defendants had filed a motion to review the source code for the Intoxilyzer 5000 breathalyzer in October.

"The defendants have established that the source code is material to their theory of defence in these cases," judges David Denkin, Kimberly Bonner and Judy Goldman wrote in their ruling dated 2 November.

"It is therefore ordered and adjudged that the State shall produce the source code for the EPROMs located in the Intoxilyzer 5000 instruments … within 15 days of this order."

An EPROM (Erasable Programmable Read-Only Memory) is a chip that holds the software running the breathalyser.

The panel of judges appointed Harley Myler, a professor in the Department of Electrical Engineering at Lamar University in Texas, to review the code. He also acted as an expert witness for the defence.  

Myler will be prohibited from distributing any copies of the code, and has to return the code to the state following his review.

Florida approved the Intoxilyzer 5000 in 1993, but the manufacturer, CMI of Ownsboro, Kentucky has since made numerous changes which defence lawyers argue have not been certified. 

The lawyers have also alleged that CMI had to recall its devices in at least one case due to a software error.

Myler testified that there appeared to have been changes in the software, but that he could not ascertain whether the changes were substantial without viewing the source code.

CMI has so far refused to discuss the case publicly and did not return phone calls seeking further information following the ruling.

Florida Assistant State Attorney Jason Miller expressed his disappointment at the ruling, and said he plans to file an appeal.

The state is unable to comply with the ruling because it does not own the source code for the breathalyser, and CMI is refusing to hand it over because it considers the code a trade secret.

"The people who have it won't give it out. Our hands are tied here," Miller told vnunet.com. "This ruling seems to be an effective suppression of all the breath tests."

Miller added that even without the evidence of the breathalyser test he would succeed with the drink-driving cases. "Our biggest concern is the safety of the public," he said.

But Robert Harrison, one of the defence attorneys, insisted that the state should go back to CMI and ask the company to agree to the independent audit. 

"They should ask CMI whether, under these restrictive conditions, they would turn it over. They would be foolish not to try again," Harrison told vnunet.com. 

The ruling forcing the state to provide the source code was sparked by a Florida law and previous rulings in the state that seek to protect the rights of accused drink-drivers from faulty electronics.

"It seems to us that one should not have privileges and freedom jeopardised by the results of a mystical machine that is immune from discovery, that inhales breath samples and that produces a report specifying a degree of intoxication," a February 2004 court ruling stated.

While the state has provided manuals and schematics for the device it had refused to release its source code, siding with CMI's trade secret argument.

The judges, however, ruled that releasing the source code would not result in any "irreparable harm to the manufacturer", arguing that the defendants' rights to verify the source code outweighed the alleged trade secrets.

If CMI keeps refusing to subject the application to an independent audit, it is unlikely that a judge can force it to do so. This would render the results of the test inadmissible in court.

Accused drink-drivers have filed similar cases in other Florida counties. Judges have denied requests to view the source code in half a dozen cases.

While the November ruling in Sarasota is the third case where a judge granted defendants access to the code, it is the first time that the ruling was made while the judge knew that the state could not comply with the order.

The Florida case is unique but is unlikely to set a precedent for other states or countries because of the local laws.

But the discussion represents a growing trend where the rulings made by computers are being questioned in areas such as voting machines and other devices, according to Matt Zimmerman, staff attorney at the Electronic Frontier Foundation. 

"Florida seems to be on the cutting edge in that area," he told vnunet.com, adding that there is a strong lobby from enterprises to prevent legislation that would increase the access to source code.

He is not surprised by CMI's refusal to grant access to its code. "You're going to see companies keeping a tight lid on their own source code if they are not required by law to open it," said Zimmerman.

"They consider it a competitive disadvantage if they are forced to make that code available."