Colorado State Patrol is in the middle of a 3-year-long DUI marijuana pilot program, testing new devices they hope will help them catch marijuana impaired drivers.

"Every device is different. Some tell you to swab above the tongue, some below the tongue," said Major Steve Garcia, CSP's Training Services Branch Commander.

In March, 150 troopers across the state started using one of the five devices that tests for THC levels in a person's system through saliva. They're evaluating how easy each device is to use and how accurate they are at determining whether someone is driving high.

"It can tell you not only about marijuana but the other seven types of drugs and their levels of impairment," Garcia said.

Colorado law says a driver is marijuana impaired when they have more than 5 nanograms of THC in their blood. When a person is arrested on suspicion of driving high, troopers first give them a blood test and then ask them if they would like to volunteer in the DUI Marijuana Pilot Program. So far, they've given fewer than 100 tests.

"We're averaging around a 5 percent participation rate in the program. It has been a challenge, but we need to evaluate these devices," Garcia said.

Colorado State Patrol stressed the tests are voluntary and don't influence an officer's decision to arrest someone. It's unclear how they could affect pending DUI cases in court. The test results are discoverable by the defense, which means they could bring them up should they choose.

Garcia said they hope the data collected from the tests will also give them a better idea of how many marijuana impaired drivers are on Colorado roads and whether that number has increased since Amendment 64 was passed.

The $200,000 program was funded by the marijuana task force.

Garcia said CSP will evaluate the devices in March and then roll them out for other departments to pilot in April. They want to collect at least two years worth of data before making any decisions on what device to use, if they choose one at all.