Trial and Error (1997)

Directed by Jonathan Lynn

When lawyer Charlie is sent to a small Nevada town to file a continuance request for a client, his actor friend Richard turns up to throw a surprise bachelor party celebrating his upcoming marriage to the boss's daughter. When Charlie is too hung-over to make it to court for the hearing, Richard fills in, inadvertently committing felony fraud, and Charlie is left with no choice but to coach the clueless Richard through the whole trial.