A district attorney or prosecutor has the discretion to decide which crimes should be charged. In a typical scenario, the police investigate a crime and send a report to the prosecutor. The prosecutor then must decide whether to bring criminal charges against the subject of the investigation. The first thing the prosecutor looks for is a legally sound case. The case must not have any obvious defects that will get it thrown out of court, such as violation of the defendant's constitutional rights or destruction of evidence crucial to the defense. The prosecutor next decides if there is reliable evidence of the person's guilt. The prosecutor must determine that the amount of evidence, and the quality of evidence, makes conviction probable. Finally, the prosecutor decides if the case fits in with the office's policy objectives. If pre-trial diversion is available, such as an agreement by the defendant to undergo drug treatment in return for a suspended sentence, the prosecutor may prefer to dispose of the case that way. The defendant's culpability may be lacking because he acted out of a worthy motive, or has mental defects. Finally the prosecutor must decide if he has the resources to pursue the case or if it is a low priority for that particular office.

Many prosecutors are elected officials and as such can be voted out of office if the public does not like the emphasis of their office. Some prosecutors, for instance, may focus most of their efforts and the office's resources combating property crime, while others may focus on domestic abuse. If the electorate does not like the particular goals of the prosecutor, it can end the practice by failing to reelect the individual or by seeking to have them otherwise removed from office.