In 1969, the U.S. Supreme Court ruled that the Speaker of the House could not exclude a duly-elected candidate for the U.S. House of Representatives. In [Adam Clayton]Powell v. McCormack, 395 U.S. 486 (1969), the Supreme Court ruled that the House's Constitutional authority to judge the qualifications of its own members was post facto and could only be exercised via expulsion after a 2/3rd affirmative vote. In other words, the House and Senate have no discretion when deciding whether to seat a candidate who has been duly elected under state law, but may take steps to expel that member after they have been sworn-in.
In 1969, the U.S. Supreme Court ruled that the Speaker of the House could not exclude a duly-elected candidate for the U.S. House of Representatives. In [Adam Clayton]Powell v. McCormack, 395 U.S. 486 (1969), the Supreme Court ruled that the House's Constitutional authority to judge the qualifications of its own members was post facto and could only be exercised via expulsion after a 2/3rd affirmative vote. In other words, the House and Senate have no discretion when deciding whether to seat a candidate who has been duly elected under state law, but may take steps to expel that member after they have been sworn-in.