 Emerson has been criticized by Hawaiian royalists and historians for being a founding member of the Hawaiian League of 1887, which authored the Bayonet Constitution forced on King Kalākaua, under threat of death.An original copy of the 1887 constitution in the Hawaii State Archives, once owned by William Owen Smith, contains a side notes written by Smith listing Emerson as one of the main contributors to the constitution alongside Smith, Sanford B. Dole and Lorrin A. Thurston.He was also criticized for testifying in Washington, D.C. in support of the annexation of Hawaii.