Driving or operating a motor vehicle under the influence of marijuana is a crime in the state of Connecticut. Your first offense is a mandatory 48 hours in jail and fines. They will know right away if you are impaired as they have trained narcotics officers which use a very specific protocol to make the final determination.
Yes, you can get a DUI if you are caught driving under the influence of marijuana in Connecticut, just like any other controlled substance. If the officer believes you are under the influence of marijuana they will administer a field sobriety test which will check and monitor your behaviors. If you fail this test you will be arrested and charged with a DUI or some equivalent. Marijuana is treated roughly the same as alcohol.
Yes you can receive a DUI from smoking weed in Connecticut. Police officers are trained to detect if someone may be impaired by THC drugs, they will give you a physical test similar to an alcohol test. If you fail you will submit to a urine/blood test, which detects if you were too high to drive.