[4] During World War II, he served with the U.S. Army Air Forces in the judge advocate general's department in the European Theater (1942–1945).

[4] In 1958, Moss ran for the U.S. Senate against two-term incumbent Arthur V. Watkins, a close ally of both the Eisenhower administration and the Church of Jesus Christ of Latter-day Saints (see also Mormon), and also against J. Bracken Lee, a non-Mormon and former two-term Utah governor (1949–1957), who was running as an independent after losing to Watkins in the Republican primary.

Moss was an original sponsor of laws to create Medicaid, a program to cover health care for low income people.

[6] Moss was elected to a second term in 1964, defeating Brigham Young University President Ernest L. Wilkinson.

He worked to secure additional national parks for Utah and started important investigations into the care of the elderly in nursing and retirement homes, and into physicians' abuses of the federal Medicaid program.

In 1976, his capacity as chairman of the U.S. Senate Subcommittee on Long-Term Care, Senator Moss made a first-hand investigation of waste, fraud and mismanagement in the Medicaid program by posing as a patient and visiting the East Harlem Medical Center in New York City.

[7] In 1974, Moss joined Senator Frank Church (D-Idaho) to sponsor the first legislation to provide federal funding for hospice care programs.

[9] Moss chaired the Consumer Subcommittee of the Senate Commerce Committee where he sponsored a measure, the Cigarette Labeling and Advertising Act of 1966, requiring detailed labeling on cigarette packages noting the health hazards of smoking and banning tobacco advertising on radio and television.

[11] Hatch won the election by an unexpectedly wide nine-point margin and proceeded to hold that seat for the next 42 years.