He was a prominent lawyer in Lancaster, Pennsylvania, and was one of the first judges appointed to the Supreme Court of the Wisconsin Territory when it was established in 1836.

His father, also named William Clark, was a Captain of the Delaware light cavalry during the American Revolutionary War.

Judge Frazer never fully relocated to Wisconsin, but held court at De Pere and Milwaukee on several occasions.

He was said to have fallen into "intemperate habits" that had impaired his mental and physical health, and his manner was described as nervous, impatient, arbitrary, harsh, overbearing, and offensive.

A petition campaign was organized to seek Judge Frazer's resignation and, in September 1838, he wrote that he would retire in October.