The Kudos production is currently shooting principal photography for the six-part series, which has been penned by Ashley Pharoah and Matthew Graham.
Samuel West (Any Human Heart, Van Helsing) is cast as Zak Gist, an angel sent down to earth to help a community, while Ukweli Roach (Streetdance 3D) plays angel newcomer Tom Greening who is always getting into scrapes. The pair work as lawyers and they attempt to highlight humans' failings and faults through their work.
Hattie Morahan (Sense and Sensibility, Lark Rise to Candleford) plays a love interest for Zak and Tobias Menzie is adversary and dark angel Richard Pembroke.
Mistresses and Fringe actress Orla Brady plays the enigmatic and glamourous Mrs Sheringham, who keeps Zak and Tom in line.
Controller of drama commissioning Sally Haynes said: "Eternal Law is a unique and original drama from two of the country's best and most imaginative writers. They have created two brilliant characters in Zak and Tom and I'm delighted we're shooting this in the spectacular city of York."
Ashley Pharoah added "This idea has been a passion of ours for some years now and we always thought its natural home was ITV. To make it with our friends and long-term producing partners at Kudos just makes it that much more exciting."
Eternal Law will air in 2012.