DENVER (CBS4) – The heat is on this holiday weekend. Police across Colorado are cracking down on impaired drivers. This year they’re looking not only for drunk drivers, but also drivers under the influence of marijuana.

Police have already made hundreds of arrests this weekend. So far the flashing lights seen at DUI checkpoints and saturation patrols have resulted in 730 people being arrested for impaired driving. Officers say more and more of those DUIs include people high on drugs, which isn’t as easy to detect behind the wheel.

“We’re seeing a lot more people doing drugs, marijuana and cocaine,” Cpl. Heath Griscavage with the Colorado State Patrol said.

Campaign posters even aim at drivers who are legally allowed to be medicated by a prescription. Sgt. Jim Gerhardt with the Colorado Drug Investigators Association says even with a prescription, impairment is illegal behind the wheel.

“What medical marijuana has shown us is that when we open the door and allow for it, we have these bad consequences,” Gerhardt said.

The recent campaign says those who drive impaired by drugs, even if they have a prescription or medical marijuana card, will be arrested for DUI.

The Colorado Department of Transportation says drug-impaired driving is a serious problem. From 2006 to 2010, 16 percent of all fatalities in Colorado involved drivers who tested positive for drugs.

Some medical marijuana supporters say the campaign is concerning to them. They say it’s not illegal to use your prescribed medicine and get behind the wheel.

“What is a violation of the law is to be impaired,” said Robert Corry, a medical marijuana attorney. “I’ve talked to many patients who tell me it would be unsafe for them not to drive while they’re medicated because then they’re suffering from their debilitating medical condition … many patients tell me they don’t even get a buzz from marijuana, all they get is the absence of pain.”

“The more legal, the more accessible you make something, the more then you have the negative impacts and people live in denial about that,” Gerhardt said.

The Medical Marijuana Industry Group says they support the CDOT message in the campaign and medical marijuana patients should not medicate and drive.

CDOT says the number of officers trained to spot drug impairment has significantly increased.