Hagen is experienced in real property, equity, bankruptcy and insolvency. His practice has expanded to briefs for administrative, international and constitutional law.
He regularly appears in the Supreme Court of New South Wales, the Federal Court of Australia, the Administrative Appeals Tribunal, and the NSW Civil and Administrative Tribunal. He has also appeared, without a leader, in the High Court of Australia. He accepts private briefs and briefs from Legal Aid New South Wales.
Hagen holds a Master of Laws and a Bachelor of Economics from the University of Sydney. He holds a Bachelor of Laws with Honours from the University of New South Wales.
Prior to being called to the Bar, Hagen practised as a solicitor in insolvency at Blake Dawson, now Ashurst, and was tipstaff to the Honourable Justice George Palmer AM QC.
Stephenson v Santos  NSWCA 262
The Owners Strata Plan No 2245 v Veney  NSWSC 134
Burns v Corbett; Gaynor v Burns  HCA 15
Toyota Finance Australia Limited v Gardiner  NSWCA 162