Your blood alcohol level changes with time. You may actually have more alcohol in your blood after drinking than you did while you are drinking. The Colorado “Per Se" law requires that you be tested within two hours of the last moment you were known to have driven. However, even if the police fail to test you within that time, the prosecutor can instead try to convict you in a different way, by convincing the jury that you were “substantially impaired.”
Per Se Laws
Laws that declare it illegal to drive a vehicle above a certain alcohol level, as measured by a blood or breath test. The only question is whether the driver was above the legal limit at the time of driving.
The government lawyer who investigates and tries criminal cases. Typically known as a district attorney, state's attorney, or United States attorney.