It is illegal to have five nanograms or more of pot in your system while driving. A blood test is required to detect marijuana in a driver's system.
Memorial Hospital says pot can stay in your system for 30 days. If you think you're safe because you don't look stoned, think again.
It's nothing new. You can't drink and drive and you can't be on drugs while driving, but now that it is legal to buy marijuana in Colorado, confusion is a common thread.
"While driving I would imagine it's illegal," said Colin Cruz.
"I would say you can't have any marijuana in your system while you're driving at all," said Darin Bible.
"It is illegal? No, I did not [know that]," said Quailla Evans.
If a law enforcement officer suspects you've been driving under the influence of marijuana, the officer will have to take you to likely a hospital to take a blood test. It will take two to three weeks for the results.
"It would not surprise me if we pick up more persons under the influence of drugs," said Colorado State Patrol trooper Jim Schmidt.
If more people are suspected of driving while stoned, that means more blood tests.
"I understand the reason why they can't do a simple breathalyzer on it, but it my opinion I think it's a little ridiculous," said Evans.
Relying on an officer's training to bring you in for a blood test has mixed opinions.
"If it keeps people safe, I guess it's worth it," said Cruz.
"Especially the users that are using it every day know how to get ride of the smell. It's going to be hard to detect," said Bible.
However, that is where the blood tests and training come in.
"Every one of us knows what's going on with it and every one of us has to be more cognizant of it," said trooper Schmidt.
You can refuse a blood test, but the consequences include losing your driver's license.
Memorial Hospital said it does not anticipate an increase in blood test patients, but will be ready just in case.
Some counties in Colorado such as Douglas County allow paramedics to do on site blood tests. El Paso County does not allow it.