He earned a Bachelor of Science degree in business and finance from the University of Utah in 1955, where he was a member of the Sigma Chi fraternity.

Garn was re-elected to a second term in November 1980 with 74 percent of the vote, the largest victory in a statewide race in Utah history.

Though strongly anti-abortion, Garn joined United States House of Representatives member Henry Hyde of Illinois in resigning from the board of the United States anti-abortion movement when the executive director of the organization, Peter Gemma, issued a "hit list" to target certain lawmakers who supported abortion rights.

Gemma said that he was surprised by the withdrawal of Garn and Hyde from the PAC committee but continued with plans to spend $650,000 for the 1982 elections on behalf of anti-abortion candidates.

Garn asked to fly on the Space Shuttle because he was head of the Senate appropriations subcommittee that dealt with NASA, and had extensive aviation experience.

Garn said that flying on the Shuttle would be a fact-finding trip: "I do really think that it is a necessity that Congressmen check things out that they vote for and make certain that funds are being spent adequately.

Its primary objective was to deploy two communications satellites, and to perform electrophoresis and echocardiograph operations in space in addition to a number of other experiments.

As a payload specialist, Garn's role on the mission was as a congressional observer[12] and as a subject for medical experiments on space adaptation syndrome.

[13] Some NASA astronauts who opposed the payload specialist program, such as Mike Mullane, believed that Garn's space sickness was evidence of the inappropriateness of flying people with little training.

[4] Fellow 51-D payload specialist Charles Walker—who also suffered from space sickness on the flight despite having flown before—stated that: He worked out extraordinarily well, and quite frankly, I think the U.S. space program, NASA, has benefited a lot from both his experience and his firsthand relation of NASA and the program back on Capitol Hill.

As a firsthand participant in the program, he brought tremendous credibility back to Capitol Hill, and that's helped a lot.

[15][16] On April 8, 1977, he married Kathleen Brewerton, who had a son, Brook, from a previous marriage at Salt Lake Temple.