In 1906, he became a Judge of the Circuit Court of Cook County, Illinois, serving until 1910.

[1] Carpenter was nominated by President William Howard Taft on December 13, 1909, to a seat on the United States District Court for the Northern District of Illinois vacated by Judge Solomon H. Bethea.

He was confirmed by the United States Senate on January 11, 1910, and received his commission the same day.

[1] Carpenter presided over the trial of Jack Johnson under the Mann Act and passed sentence.

[2] Following his resignation from the federal bench, Carpenter returned to private practice in Chicago from 1933 to 1944.