 He succeeded Sir John Wemyss of Craigtoun as an ordinary lord of session, 18 December 1623, and retained his seat in 1626, when many of the lords were displaced.In 1630, he was placed on a commission upon Scots law, and in 1633 was a member of commissions to revise the acts and laws of Scotland with a view to constructing a code, a project which was not proceeded with, and to report upon the jurisdiction of the admiral and chamberlain.He was also ordered to examine Sir Thomas Craig's work "Jus Feudale", with a view to its publication.