His ruling in Marie Louise v. Marot was cited as precedent by dissenting U.S. Supreme Court Justice John McLean in the 1856 landmark Dred Scott v. Sandford case.

He originally set out to become a physician but was persuaded by his father to study law under his brother, John Mathews, in Augusta, Georgia.

[4] In 1804 Mathews was appointed by President Thomas Jefferson to be judge of the Superior Court of the newly created Territory of Mississippi.

[1] He reputedly learned both French and Spanish as much of the law of the State of Louisiana was rooted in the traditions of the land's previous colonial overlords and many lawyers spoke one of the two languages but not English.

Mathews, speaking for the court, stated that "[b]eing free for one moment...it was not in the power of her former owner to reduce her again to slavery.

[7] He left a very large fortune at his death, and his will was successfully attacked; one of its dispositions being annulled by the Louisiana Supreme Court.