On January 5, 1942, Mayne married Betty Dodson. The couple had three children; sons Wiley Mayne II and John Mayne, both of whom followed in their father's footsteps and became lawyers, and daughter Martha Mayne Smith.[3]
As a member of the House Judiciary Committee, Mayne played an influential role in amendments to the Federal Rules of Evidence, especially those involving the admissibility of opinion testimony. His political downfall, however, came in his fourth term during his service on that Committee, when Mayne was one of ten Republican Committee members to vote against articles of impeachment against PresidentRichard Nixon arising from the Watergate scandal. At the time of his Committee votes, Mayne believed that the proof was not sufficient to necessitate a call for impeachment. In Nixon's final days in office, however, Mayne's opinion quickly changed after evidence implicating Nixon in a subsequent coverup was made public, and he vowed to vote in favor of impeachment when the articles came before the full House.[4] The damage, however, had been done, and Mayne narrowly lost the 1974 election to his 1972 opponent, Democrat Berkley Bedell.[6]
Later life
After leaving Congress, Mayne returned to Sioux City, Iowa, to resume his law practice.[3] His wife, Betty, died in 2001, and Mayne continued to practice law until 2005.[3] Mayne died in May 2007 after suffering a cardiopulmonary incident.[citation needed]