The police must adhere to strict procedures and laws when they arrest someone. An arrest is considered an extreme invasion of a person's liberty, therefore, the government must have an excellent reason to do it. Failure to observe these rules could result in the exclusion of evidence gathered as a consequence of the unlawful arrest or even release from custody. This post will go over the situations in which drunk driving could result in each of these scenarios.
First, if the officer sees you commit a crime, she may arrest you. For drunk driving, if the officer observes you drinking while behind the wheel, that constitutes a crime for which she may arrest you.
Second, police officers can arrest you if there is probable cause to believe that you committed a crime. There is probable cause if the officer reasonably believes, based on the situation, that you committed a crime. Unlike above, in which the officer saw you drink, this situation is based on the field sobriety test, the smell of alcohol on your breath, and other factors that could lead to a reasonable inference that a crime was committed.
Finally, officers may arrest you under an arrest warrant. For drunk driving, this will not come up too often because the evidence that supports these charges expires after a few hours (BAC levels). But it is possible for these to be issued if you fail to appear at a court hearing for your drunk driving charge.
If you were charged with a crime, you might want to contact a criminal defense attorney. A lawyer can go over the law with you and help you craft a defense strategy or argue for a plea bargain. Regardless of your criminal defense choices, a lawyer can work to get you better results.