Pretrial is the time period after an individual has been arrested but before their case has been adjudicated. During this time period, a U.S. Pretrial Services Officer will gather information about the defendant through interviews and record checks. The U.S. Pretrial Services Officer reports the information to the judge, so the judge can decide whether the defendant can be released on pretrial supervision or should be detained.

At a detention hearing, the judge will decide whether or not to grant pretrial release. If the defendant is granted pretrial release, the U.S. Pretrial Services Officer will supervise the defendant to ensure 1) they are not a danger to another person or the community, 2) the conditions of their release are met, and 3) they attend all required court hearings.

Pretrial supervision ends if the defendant is found not guilty at trial or the charges are dropped against him or her. If the defendant is found guilty or pleads guilty, the U.S. Pretrial Services Officer will typically continue supervising the defendant until their sentence begins. Pretrial supervision usually lasts a few months, during which time a U.S. Probation Officer may start the defendant's presentence investigation.