Thomas Todd was born and raised in Virginia. At 16, he served in the Revolutionary War. Following his graduation from Liberty Hall (now Washington and Lee University), Todd tutored the daughters of a distant relative in return for room, board, and law instruction. Todd later moved to the area of Virginia that would become Kentucky. He was intimately involved in the statehood issue and was appointed by Kentucky's first governor to serve on the state's highest court.
In 1807, Congress increased the membership of the Supreme Court from five to six. Jefferson selected Todd for the seat because of his familiarity with land law problems, especially those arising from the newly created western circuit of the Supreme Court (Ohio, Kentucky, and Tennessee).
Todd served for 18 years but did not write a single constitutional opinion. In fact, he wrote a total of fourteen opinions, and most of those involved land law issues. He missed five entire Court sessions on account of personal or health issues.