Article I, Section 5 of the Constitution declares that "Each House shall be the judge of the elections, returns and qualifications of its own Members." But despite granting those authorities to Congress, the Constitution is silent on why the House or Senate might not seat someone. Besides the House and Senate expelling someone, a governor must declare a seat vacant. The House then voted to declare her seat vacant, compelling Maryland to hold a special election. But once someone is in a House or Senate seat, they’re in.