Randolph W. Thrower, a Republican lawyer who headed the Internal Revenue Service under President Richard M. Nixon from 1969 to 1971 before losing his job for resisting White House efforts to punish its enemies through tax audits, died March 8 at his home in Atlanta. He was 100.

A daughter, Patricia Barmeyer, confirmed the death.

Mr. Thrower’s unusual legal background — as a federal tax law expert and a lawyer for death row inmates in Georgia, most of them black, in the Jim Crow era — helped garner wide support from lawyers’ groups and lawmakers when Nixon nominated him for I.R.S. commissioner.

And though his tenure was short, he was instrumental in two historic overhauls of American tax policy: revoking the tax-exempt status of private schools that excluded blacks, and passage of the Tax Reform Act of 1969, which he helped draft. The legislation eliminated some loopholes for the rich and exempted many poor people from federal taxes altogether....