To convict someone of a criminal offense, the state must prove beyond a reasonable doubt that the accused broke the law. Before a police officer can arrest you, they need probable cause to believe a criminal act has occurred.
Just making a few mistakes at the wheel may not be justification for a police officer to arrest you. How does the police officer build a case that you were under the influence of drugs or alcohol?
They ask you questions
Most drunk driving cases start with the police officer talking to the allegedly impaired driver. How someone answers a question that a police officer asks them can directly lead to their arrest in some cases. If someone admits to drinking too much or too using certain medication, the police officer can potentially arrest them at that point.
They perform tests
If an officer thinks you might have had too much to drink and your answers to the questions they asked aren’t enough to give them a reason to arrest you, they may ask you to step out of the vehicle to perform several field sobriety tests.
Your performance on those tests may then give an officer the reason that they need to ask for a chemical breath test. The results of those tests will often lead to an officer arresting a driver and will likely form the basis of the upcoming prosecution for the driver in question.
If you want to defend against drunk driving allegations, you may want to develop an alternate explanation for what happened during the traffic stop or challenge the traffic stop. Understanding how the state builds drunk-driving criminal cases can help those hoping to defend against pending charges.