Mark is currently Visiting Practitioner at the Centre for American Legal Studies at Birmingham City University and is on the editorial panel for the British Journal of American Legal Studies.
In 1998 he worked pro bono in a capital murder trial in Texas where he assisted the local attorneys with the preparation of the case for trial. This involved being temporarily admitted as a member of the Texas Bar. Since that time he has been involved with Amicus, an organisation which trains young lawyers to undertake internships in the US assisting in death penalty trials and appeals.
He regularly teaches at the Amicus training sessions in trial procedures in capital cases, jury selection and mitigation issues. He also teaches on appeals in state and federal courts in capital cases. Each autumn, subject to availability, he delivers a popular lecture tour on "death penalty in the US" to a number of law schools and universities across the UK.
He has also written a number of articles for the Amicus Journal on aspects of US death penalty law. In 2008 Mark became a trustee of the charity.
Mark has been involved with writing Amicus Curiae briefs in four US Supreme Court cases.
- In 2009 he assisted in writing a brief on behalf of the BHRC outlining the UK position on life sentences for young offenders in the UK in the case of Graham v. Florida where the challenge was against life without parole for those aged under 18.
- In 2011 he helped draft an amicus curiae brief in the case of Manuel Valle on death row in Florida for over 33 years in which he argued that comparison with the position in UK law showed that execution after such a length period on death row together with the failure to provide a meaningful clemency process would contravene international law standards.
- In 2012 he assisted in writing a brief on behalf of the BHRC in support of the main petition and which argued the international perspective as well as citing the law in England & Wales on the sentencing of juveniles convicted of murder in the case of Miller v Alabama heard together with Jackson v Hobbs from Arkansas where the challenge was against life without parole for juvenile murderers.
- In 2015 in a challenge in the US Supreme Court to the continuing constitutionality of the death penalty by an inmate on death row in Pennsylvania he wrote part of an amicus brief on behalf of the BHRC setting out the arguments that led to the abolition of the death penalty in the UK in the 1960s – Walter v. Pennsylvania