Justice Hammerschlag was born in Johannesburg, South Africa. He did two years full time compulsory military service in the South African Defence Force including a period as a military law advisor in which capacity he appeared in numerous courts martial. He was called to the South African Bar in 1982. He moved to Australia in 1986, and re-qualified in New South Wales by way of Solicitors Admission Board examinations. He worked for the law firm now known as Herbert Smith Freehills (then Freehill Hollingdale and Page) and was admitted to the partnership in 1988. He was called to the New South Wales Bar in 1991 and took silk in 2000. He was a founder member and later Chairman of 11 St James Hall Chambers. He appeared in major commercial disputes and white collar criminal prosecutions, and in the HIH and Orange Grove Royal Commissions. He was appointed to the Supreme Court of New South Wales in 2007 and sat initially in the General List of the Equity Division. He was appointed Corporations List Judge in 2008 and head of the Commercial List and the Technology and Construction List in 2009. He is also the Commercial Arbitration List Judge. He has sat on the Court of Appeal and the Court of Criminal Appeal. He appeared in major commercial disputes and white collar criminal prosecutions, and in the HIH Royal Commission and the Orange Grove ICAC Enquiry.