Bratza was appointed Junior Counsel to the Crown at Common Law in 1979 and took silk as Queen's Counsel in 1988. He acted in 1981 for the UK Government at the European Court of Human Rights against Jeffrey Dudgeon who complained successfully that the law in Northern Ireland, which made homosexual acts between consenting adult males a criminal offence, was a breach of the Convention. In 1993, Bratza was appointed a Recorder of the Crown Court and elected a Bencher of Lincoln's Inn. In the same year, he was appointed as the UK Member of the European Commission of Human Rights, part of the European Convention on Human Rights system of the Council of Europe. In 1998, the Commission was abolished and replaced by a permanent European Court of Human Rights, and Bratza was elected as the Judge of this Court representing the United Kingdom. The eligibility criteria for appointment, however, required that Bratza hold judicial office in his home territory, and for this reason he was appointed a High Court judge. This afforded him the title The Hon. Mr. Justice Bratza, but at the European Court he is referred to simply as Sir Nicolas Bratza. In the same year, and again in 2001, he was elected as one of the five section presidents of the court. He was elected to a second and final term as a judge of the court and re-elected as a section president in 2004. He was a vice-president of the court from 19 January 2007 to 3 November 2011. In July 2011, he was elected to succeed Jean-Paul Costa as President of the court on 3 November 2011. His term on the court ended on 31 October 2012, and he resigned as a Justice of the High Court on 1 November 2012.
Other appointments
Bratza was appointed as President of the British Institute of Human Rights Advisory Board in February 2013, a member of the Advisory Board of the British Institute of International and Comparative Law, a member of the Editorial Board of the European Human Rights Law Review and a member of the Advisory Board of the European Human Rights Association. In June 2007, he received the degree of Doctor of Laws, honoris causa, from the University of Glasgow. In 2014, Bratza became an ambassador for Toynbee Hall. It marked a return to the East London charity, where he had volunteered at its Free Legal Advice Centre during the late 1970s and early 1980s. In 2018, Bratza became a member of the Executive Committee of the International Commission of Jurists, having served as a Commissioner since 2013.