In spite of his being under indictment at the time, the voters of Milwaukee elected Berger to the House of Representatives in 1918. When he arrived in Washington to claim his seat, Congress formed a special committee to determine whether a convicted felon and war opponent should be seated as a member of Congress. On November 10, 1919, they concluded that he should not, and declared the seat vacant. He was disqualified pursuant to Section 3 of the Fourteenth Amendment to the United States Constitution. Wisconsin promptly held a special election to fill the vacant seat, and on December 19, 1919, elected Berger a second time. On January 10, 1920, the House again refused to seat him, and the seat remained vacant until 1921, when Republican William H. Stafford claimed the seat after defeating Berger in the 1920 general election.