From 1849 to 1850, he was senior defense counsel (co-counsel with Edward Dexter Sohier) in the trial of Harvard University Professor John White Webster, accused of murdering Harvard patron Dr. George Parkman.

In 1853, Merrick was promoted to the bench of the Supreme Judicial Court by the same John H. Clifford, now Governor of Massachusetts.

The party developed in the early nineteenth century, opposing political leaders who were members of secretive Masonic brotherhoods.

Masonic members held political views on the role of the government and how the country should expand.

The Anti-Masonic Party opposed those views as moving away from the original founding fathers intent.

His obituary in the New York Times (2/4/1867) stated: "In 1864 an attack of paralysis obliged him to resign his seat on the Bench.

His mind, however, had remained unclouded until a second and fatal attack..."[8] He bequeathed a fund for the establishment of schools of high grade in Worcester.