"Congress can hold a person in contempt if their actions are viewed as obstructing legislative business or a congressional investigation.
Lawmakers have three routes:
Inherent contempt: The Supreme Court has ruled that lawmakers have inherent contempt powers to have an individual held until the person "provides the testimony or documents sought, or until the end of the session," reads a 2017 report from the Congressional Research Service, Congress' policy research arm. Using this process is incredibly rare and hasn't been done in modern times, not since the 1930s.
Criminal contempt: Congress also has the option to use its "criminal contempt" powers, a law that allows lawmakers to charge an individual with a crime. This is the process listed above with regard to Barr that's more common and would have to be passed through one of the chambers in Congress.
Civil judgment: The third option is going through a civil process in the courts. Lawmakers can seek a civil judgment, asking a judge to enforce a subpoena.
The most common method used by Congress has been criminal contempt; a charge is a misdemeanor and punishable by jail time of between a month and a year and a fine."
