The Los Angeles Times reports:
Less than a month after he battles for re-election Nov. 6, Rep. Duncan Hunter, R-Calif., is expected in a courtroom to face felony charges that he misused campaign contributions. If Hunter wins re-election and is subsequently convicted, there is no constitutional provision or House rule that explicitly requires him to lose his seat, even if he is imprisoned and unable to vote on behalf of his district. Whether he would be pressured to resign could largely depend on which party comes out on top in congressional elections.
House rules do advise — but do not mandate — that a sitting member sentenced to two or more years in prison step down from committees and refrain from voting. In the case of conviction, the leader of the majority party can ask — and pressure — a member to step aside. But the only way a member would be forcibly removed is by expulsion. If Republicans remain in charge, they will have to weigh whether to chance losing a GOP seat (though Hunter’s district leans conservative) in a required special election.