A criminal charge is like a civil lawsuit in one respect, the time limit for filing against the defendant. The federal statute of limitations that applies to criminal charges says that once 5 years has passed from the commission of the offense, the federal government is barred from filing charges.
The federal statute of limitations is 18 USC 3282, and it provides the following:
Except as otherwise expressly provided by law, no person shall be prosecuted, tried, or punished for any offense, not capital, unless the indictment is found or the information is instituted within five years next after such offense shall have been committed.
See 18 USC 3282(a).
The purpose of the statute of limitations is to protect defendants from having to defend themselves against charges concerning events that took place long in the past. Evidence they would use to prove their innocence may no longer be available through no fault of their own. It would arguably be a violation of due process for a prosecution to take place in these circumstances.
The statute of limitations is a complete defense to a criminal charge, but failure to raise it prior to trial is a waiver and the prosecution would be allowed to proceed.
To prevail on a statute of limitations defense, the defendant must show that the date of filing of the criminal complaint (also called an information) or indictment by the grand jury was beyond the 5-year period.
The general 5-year limitation established by 18 USC 3282 has exceptions. Federal law says that the general 5-year statute of limitations applies in every case unless there is specific statute concerning the offense.
For capital crimes (eg, death penalty cases), the United States Attorney is not subject to any statute of limitations. 18 USC 3281. Terrorism is not subject to any statute of limitations where the offense caused death or serious bodily harm, or threatened the same. 18 USC 3286. Likewise, sex offenses in which a child was the victim are also not restricted by any statute of limitations. 18 USC 3283.