They often pop up during holidays and other times when drivers least expect them.
DUI checkpoints put a lot of people in jail.
Now a pair of attorneys say some of the machines reading double vision need to be double checked.
Florida uses a breath test called the Intoxilyzer 8000, which runs on software. But attorney Mitch Stone said he and his partner helped discover that the software has different versions.
"We have reason to believe there is at least one version that is not approved and was not evaluated and would not be authorized for use in the state of Florida," Stone said.
He said there may be more. He's filed a motion in Duval and surrounding counties in hopes of finding out which software version is running on which machines, and if the software hasn't been approved, the breath test reading may not be admissible under law.
"Anyone who was convicted based upon testing on those machines would potentially be subject to having their cases looked at again," Stone said.
"It's important to note, it's not the prosecutors who are getting in the way of this information. It's the manufacturer," attorney Lee Lockett said.
He and Stone said it's their job to ensure the integrity of the process so the wrongly convicted aren't locked up.