Several factors influence when someone arrested for a Driving While Impaired (DWI) will be released from jail, including the results of their breath test, the presence of aggravating factors, and the time/day of the arrest.
If your son has not been arrested for a DWI within the last ten years, didn’t refuse to take a breath test, didn’t have children in the car, and his breath test result was below .16, he will likely be released within several hours of his arrest. Sometimes officers will hold a person in custody until they blow .00. In such misdemeanor cases, the police tend to issue a citation which includes a court date, and they will release your son to a sober adult (assuming there are no other outstanding issues or warrants).
If, however, your son refused to take a breath test or there were any aggravating factors present, he will likely be held in jail until he can appear before a judge at a First Appearance (often called a “bail hearing”). At this appearance, a judge may set bail, which is a sum of money given to the court to guarantee appearance at future hearings, or conditions for your son’s release (including no-use and alcohol monitoring).
Importantly, if your son is arrested and not released with a citation by the police, he may spend several days in jail waiting to see a judge. In Minnesota, if the police arrest someone without a warrant, (s)he must be brought before a judge no more than 36 hours after the arrest. However, the day of arrest, Sundays, and legal holidays are not subject to this rule. For example, if your son was arrested on Friday (and not cited and released), he will probably not see a judge until Monday, because Friday and Sunday don’t count against the 36-hour requirement. In the case of a legal holiday, this could be even longer.