After graduation, Gleeson spent one year as a solicitor at Messrs Murphy & Moloney. Gleeson was admitted to the
New South Wales Bar in 1963, where he read with
Laurence Street and
Anthony Mason - his future predecessors as Chief Justice of New South Wales and Chief Justice of Australia respectively. His appearances as junior counsel focussed mainly on matters of taxation and commercial law, as well as important constitutional cases including
Strickland v Rocla Concrete Pipes Ltd, which concerned the scope of the
corporations power. Upon his appointment as
Queen's Counsel (QC) in 1974, Gleeson's career as senior counsel continued to focus on commercial and constitutional matters. However he also appeared in some high-profile criminal cases, including his successful defence before a jury of
National Party MP Ian Sinclair in 1980. In the same year he appeared for the appellants in
Port Jackson Stevedoring v Salmond & Spraggon, the last case granted leave to appeal to the
Privy Council from the High Court. ==Judicial career==