His uncles Daniel and Lewis Carn were known to be American patriots and Revolutionary War veterans according to the 1835 Pension Roll.
Merrick went to South Carolina College (USC) and later studied law to become a SC lawyer.
He held many positions of local and state government, from his home seat in Walterboro, Colleton Co., SC.
Merrick died in January 1862 and was described by his cousin David Gavin, Esq., as being the most liberal minded of men.
Carn Street in Walterboro city in named after him, and is nearby his historic home.