Martens studied Dutch law at the University of Leiden in 1955, after which he lawyer was in The Hague . In 1976 he was appointed a justice of the Supreme Court of the Netherlands, he became a member of the tax division. In November 1987 he was appointed Vice President, and on October 1, 1996, he became president of the Supreme Court.
Martens was also a member of since 1983 Benelux Court , membership of the Supreme Court, Holland's highest court, is therefore required. From 1992 to 1995 he was president of that court. From 1988 to 1996 he was a member of theEuropean Court of Human Rights . Known the often sharp dissenting opinions Martens attached to judgments of the European Court were, bundling them with the title "Martens Dissen Ting" was offered to him at his retirement as president of the Supreme Court.
Upon reaching the legal leeftijgrens of 70 Martens defungeerde early 2000. In April 2000 was followed by Pim Haak . Less than a year later, Martens died.
During Martens' presidency, the judgment of the Supreme Court gave dated March 28, 1997, NJ 1997, 581, annotation WMK (Burhoven Jaspers / Crown) the losing party, NC Burhoven Jaspers rise to complaints. Background of the case was the division of property after divorce between Burhoven Jaspers and his ex-wife, who was a prosecutor at the Supreme Court. About the case were in parliament questions asked by the MP Hendriks , when the then Minister of Justice, Ms Winnie Sorgdrager , each of machinations replied that neither reasonable suspicion of criminal acts had shown  . Complaints that Burhoven Jaspers filed with the European Commission of Human Rights was declared inadmissible. Burhoven Jaspers has continued to make, including in an interview in his criticism, however, also subsequently publicized Catholic Newspaper  , see also Public antecedents register of the judiciary .