Both of Riesser's grandfathers were rabbis; his paternal grandfather was Jakob Pinchas Katzenellenbogen, rabbi in Lemberg and later Oettingen, and his maternal grandfather was Raphael Cohen, Chief Rabbi of Altona-Hamburg-Wandsbek from 1775. Yet his father, having changed the family name from Katzenellenbogen to Riesser, chose to work as a secretary at the Jewish law court of Altona before he finally became a merchant in Hamburg. After his education at the renowned grammar school Johanneum, Gabriel Riesser went to Heidelberg and Kiel, where he studied law from 1824 to 1828, writing his doctorate dissertation in Heidelberg. He became a leading advocate of Jewish emancipation. He had himself suffered discrimination because of his religion: in Heidelberg and Jena he was denied the position of a university lecturer, in Hamburg in 1829 he was not allowed to practice as a lawyer. In his application he had recurred to a privilege of equal treatment that had been granted during the French occupation. His application, however, was refused because he formally was no citizen of the city of Hamburg. In reaction Riesser in 1830 published an essay "Stellung der Bekenner des mosaischen Glaubens in Deutschland". In 1832 he founded the journal Der Jude, periodische Blätter für Religions- und Gewissensfreiheit. He also wrote a note on the emancipation of Jews for the parliament of the German stateBaden in 1833. From 1836 onwards he composed the "Jüdische Briefe" in Bockenheim near Frankfurt am Main, which were subsequently published in Berlin in 1840-42. Riesser was chairman of the Hamburg Temple Association from 1840-43. In 1840 the Senate of Hamburg passed a law stating that "künftighin auch ein oder zwei Mitglieder der hiesigen israelitischen Gemeinde, wenn sie sonst dazu qualifiziert wären, Notare werden könnten". This change of mind of the senate was brought about by the death of the Jewish notaryMeyer Israel Bresselau, who had been installed during French annexation in 1811. Riesser applied for the vacant position. From 1840 to 1857 he practised as a notary in Hamburg.
When the civil rights of the "Paulskirchenverfassung" came into effect in Hamburg on 21 February 1849, Riesser was able to become citizen of Hamburg, a rare and dear franchise at that time, which the bulk of the inhabitants did not hold. In 1859 he was elected to the Bürgerschaft of Hamburg. In October 1860 he was appointed as a member of the city's new upper court, becoming the first Jewish judge in Germany. In 1861 Isaac Wolffson, Riesser's colleague and fellow advocate for Jewish emancipation, was elected president of the Hamburg parliament, becoming the first Jewish president of a German parliament. in Hamburg Riesser was buried at the Jewish Grindel cemetery in Hamburg. When the Nazis ordered its demolition in 1937, the Ashkenazi Congregation transferred the graves, including his, to the Jewish section of Ohlsdorf Cemetery in Hamburg. There is a street named after Riesser In Hamburg-Hamm.
