Complex sentence: After thirty years as an advocate, Nairne was elevated to a Lord of Session from 1786 to 1809, and a Commissioner of Justiciary from 1792 to 1808.
Split into simpler sentences: After thirty years as an advocate, Nairne was elevated to a Lord of Session, a position he held from 1786 to 1809. He also was appointed a Commissioner of Justiciary, which he held from 1792 to 1808.