In 1600 he was put on the standing commission of the church, in 1601 appointed one of the royal chaplains, in 1605 titular bishop of Orkney, and in 1608 moderator of the general assembly.

Law, along with John Spottiswoode, David Lindsay, and Peter Blackburn, received some of James VI's episcopal appointments.

Government forces suppressing the rebellion had besieged Kirkwall Castle and utterly demolished it at the order of the Privy Council of Scotland.

The intervention of the Bishop prevented that from happening, saving the Cathedral - considered a fine example of Romanesque architecture.

[7] Through the influence of Archbishop Spottiswoode, "his old companion at football and condiscipulus", he was promoted to the archbishopric of Glasgow in 1615, where he completed the leaden roof of the cathedral.

He died in 1632 and was buried in the chancel of Glasgow Cathedral (in the south-east corner), where there is a massive monument to his memory erected by his widow.

He was a man of some learning, leaving in manuscript commentary on a part of scripture, and was commemorated by Dr. Arthur Johnston in some Latin verses.