[3][4] There, he was appointed as a district judge, and upon the resignation of Louisiana Supreme Court Chief Justice Slidell in 1855, Merrick was elected to that office.

[3] Though in politics he was "an earnest Whig and Union man", once the American Civil War had begun, he "embraced with great zeal the Southern cause".

[3] When New Orleans was occupied by Federal troops, he went with the Confederate State Government to Shreveport, where the Supreme Court met and discharged its duties.

After the war he returned to the private practice of law in New Orleans, and as of the 1890s was reported as still being an "active, persevering, and laborious practitioner at the bar".

[3] At the age of 37, he married 15-year-old Caroline Elizabeth Merrick, who went on to become noted as an American writer and temperance worker.