Carson argued numerous cases before the Supreme Courts of Pennsylvania and the United States.

Noted cases included arguing (unsuccessfully) Lone Wolf v. Hitchcock and offering for probate the William Weightman will.

[1] Carson was also noted for his extensive collection of legal papers, books, documents, and portraits.

He was appointed state attorney general in 1903 by Governor Samuel Pennypacker and served until 1907.

[2] He served as president of the American Bar Association from 1919 to 1921 and as chairman of the sub-committee of the Pennsylvania Commission on Constitutional Amendment and Revision.