When Orrin Hatch’s career in the United States Senate ends on Jan. 3, 2019, it will have spanned an audacious 42 years, or seven full terms. Assuming he completes his final term, Mr. Hatch will become the sixth-longest-serving senator ever.

His service truly has been epochal. Unfortunately, the epoch has not been a happy one. Mr. Hatch’s career reflects the sad trajectory of our times, from a Congress where legislators had differences but actually tried to legislate, to one in which legislators — especially Republicans, terrified of facing a well-financed primary from the right — do nothing of the sort.

Mr. Hatch was elected in 1976 in one of the most improbable Senate victories, still, in recent American history. He was a Mormon, but a Pittsburgher; he had moved to Salt Lake City only in 1969 (though he had earlier done his undergraduate work at Brigham Young University, in Provo). He had no political experience and few political contacts when, the day before the deadline, this complete unknown filed his papers of candidacy for the mighty United States Senate.

The incumbent was — and how strange does this sound today? — a Utah Democrat. Frank Moss had won the seat freakishly in 1958, when the Republicans split and ran two candidates. But he’d gotten himself re-elected twice and was a key leader on consumer issues. In 1976, Utah was still a centrist enough state that Moss had reason to think he’d win a fourth term.