High Court of Australia
- In 2010 Mark argued the case in the High Court of Australia on behalf of the Hells Angels Motorcycle Club, and on constitutional law grounds successfully set aside State legislation -
Wainohu v New South Wales  HCA 24 (23 June 2011).
- In 2002, Mark argued one of the largest administrative law class-actions in history in the High Court of Australia. Mark acted for 6,700 refugee plaintiffs in the High Court's original jurisdiction. The case concerned systemic denial of natural justice by the Refugee Review Tribunal - Mark acted for Muin v Refugee Review Tribunal  HCA 30; (2002) 190 ALR 601; (2002) 76 ALJR 966 (8 August 2002)
- Mark appeared in the High Court of Australia in 1986 for the British Attorney-General in the "Spycatcher Case", against the late former spy and author, Mr Peter Wright -
Attorney-General (United Kingdom) v Heinemann Publishers Australia Pty Ltd  HCA 25; (1988) 165 CLR 30 (2 June 1988). The case was ultimately determined on justiciability principles.
- Mark argued and appeared in a series of NSW cases that led to the High Court setting aside as unlawful a number of "controlled operation certificates" which had purported to authorise law enforcement “sting” operations with large amounts of cocaine being permitted to run to the streets. At the High Court stage, the case was named Gedeon v Commissioner of the New South Wales Crime Commission (2008) 236 CLR 120
- Mark appeared in the High Court of Australia in proceedings concerning the scope of discovery against the Crown and the nature of judicial immunity in representative proceedings -
Herijanto v Refugee Review Tribunal (No 1)  HCA 16; (2000) 170 ALR 379; (2000) 74 ALJR 698 (31 March 2000) and
Herijanto v Refugee Review Tribunal (No 2) (2000) 74 ALJR 703; 170 ALR 575;  HCA 21 and
Herijanto v Refugee Review Tribunal (No 3) (2000) 74 ALJR 698; 170 ALR 379;  HCA 49.
NSW Court of Appeal
- Mark appears for regulatory agencies from time to time. Mark appeared as amicus curiae (a friend of the Court) for the NSW Roads and Traffic Authority in a significant case concerning the validity of driver licence suspension notices in NSW. The matter had implications for the implementation and enforcement of national road transport laws. The Court upheld the validity of the subject suspension notice - Director of Public Prosecutions v Yigit & Anor  NSWCA 226 (Beazley & Basten JJA and Handley AJA); see also, Roads and Traffic Authority of NSW v Higginson  NSWCA 151 (Giles, Basten and Young JJA) (20 June 2011).
- Mark appeared as amicus curiae for a number of other State and Federal agencies, for example, for the Australian Securities and Investment Commission before the NSW Court of Appeal in an application by liquidators of nine companies of a restaurant chain seeking a new method of Court approved “pooling” of assets in a winding up - Re The Black Stump Enterprises Pty Ltd and Associated Companies  NSWCA 480 (Santow & Bryson JJA & Young CJ in Eq) and Re The Black Stump Enterprises Pty Ltd and Associated Companies (No 2)  NSWCA 60 (Santow & Bryson JJA & Young CJ in Eq).
Supreme Court of NSW
- Mark appeared before Justice Hall in the Supreme Court of NSW for the plaintiff in an important case on “covert” search warrants. The Court held the execution of three search warrants to be unlawful - Ballis v Randall  NSWSC 422 (Hall J).
- Mark appeared in a number of significant cases concerning prisoner's rights, particularly in seeking rights for serious offenders in high security long term facilities (such as "Super Max") - Sleiman v Commissioner of Corrective Services & Anor; Hamzy v Commissioner of Corrective Services & Anor  NSWSC 304 (Adams J) where the Supreme Court determined for the first time that prisoners have rights to personal liberty and integrity as against other prisoners and any removal of their "residual liberty" (such as being placed in a prison within a prison) gives rise to false imprisonment damages.
- Mark appeared many times as amicus curiae for the NSW Motor Accidents Authority in the early years of implementing the current compensation scheme (involving medical assessors and claims assessors making binding statutory decisions) - see, for example, Allianz Australia Insurance Limited v Crazzi and Others  NSWSC 1090 (Johnson J); Insurance Australia Limited trading as NRMA Insurance v Motor Accidents Authority of New South Wales and Mahmoud Khateib  NSWSC 1448; Allianz Australia Insurance Limited v Motor Accidents Authority of NSW and ors.  NSWSC 1096 (Sully J).
- Mark appeared in a number of significant unlawful imprisonment and domestic slavery cases for Legal Aid clients, for example, Kang v Kwan & 2 Ors  NSWSC 1187; and MIDYA v SAGRANI  NSWCA 187.
Federal Court and Full Federal Court of Australia
- In 2011, Mark argued Kutlu v Director of Professional Services Review  FCAFC 94 (28 July 2011) (Rares, Flick and Katzmann JJ) on behalf of a number of general medical practitioners in trouble with Medicare Australia and its quasi-judicial Committees. The Court held the Committees and their decisions were invalid as the Committee members were never lawfully appointed under the Health Insurance Act 1973 (Cth) (on appeal).
- Mark has undertaken significant refugee cases for many years. In Randhawa v Minister for Immigration, Local Government & Ethnic Affairs (1994) 52 FCR 437 (Black CJ, Beaumont and Whitlam JJ), Mark appeared before the Full Federal Court in a matter that established the meaning of the “internal protection” principle held to exist in Article 1A(2) of the Refugees Convention concerning the relocation of refugees within their own country of origin.
- Mark appeared in the Federal Court of Australia for the visa applicant on a deportation for character matter. The Full Court held that the tribunal below had failed to consider best interests of the applicant's children in making its decision - Wan v Minister for Immigration and Multicultural Affairs (2001) 107 FCR 133 (Branson, North and Stone JJ).
- Mark appeared many times in the Federal Court of Australia and in the Full Court of the Federal Court for bulk-billing general medical practitioners seeking review of decisions of a Medicare Australia quasi-judicial tribunal styled the "Professional Services Review Committee" which might have seen the doctors struck off from receiving Medicare payments. Significant decisions as to the proper construction of critical provisions of the Act include Oreb v Willcock (2005) 146 FCR 237 (Black CJ, Wilcox and Lander JJ); Matthews v HIC(No 1) (2006) 90 ALD 49;  FCA 195(Edmonds J); Carrick v Health Insurance Commission  FCA 984 (Branson J); Ho v Professional Services Review Committee No 295  FCA 388 (Rares J) and in Ho v Professional Services Review Committee No 295(No 2)  FCA 603(Rares J), Willcock v Do (2008) 166 FCR 251 ( FCAFC 15); (Mansfield, Emmett, Middleton JJ); Thoo v Professional Services Committee No 446  FCA 830 (4 June 2008) (Lindgren J); Selim v Lele (includes corrigendum 10 June 2008)  FCAFC 13 (27 February 2008) 13) (Black CJ, Finn & Lander JJ) (as to the validity of Medicare) and Wong v The Commonwealth (2009) 236 CLR 573  HCA 3 (as to the constitutional validity of Medicare).
Administrative Appeals Tribunal
- Mark undertook a very difficult case in the Commonwealth Administrative Appeals Tribunal in 2005. The applicant was the victim of "bastardisation" at the Australian Defence Force Academy and he sought (and obtained in the AAT) Commonwealth workers compensation for his long-term injury. The Federal Court dismissed the Commonwealth’s appeal - Military Rehabilitation & Compensation Commission v SRGGGG (2005) 215 ALR 459; (2005) 40 AAR 337;  FCA 342 (Madgwick J) In the AAT, in Re “SRGGGG” and COMCARE (Department of Defence) - (2004) 80 ALD 778 (Senior Member M D Allen RFD, Members Dr J D Campbell and M A Griffin).