Justice Janusz Trzciński was born on 1 July 1942 in Kuńkowce near Przemyśl. He graduated from the Faculty of Law and Administration of Wrocław University in 1965. Judge Trzciński earned his juris doctor degree in 1971, and a habilitated doctor's degree in 1978. In 1986 he was awarded the title of professor of legal studies and, since 1994, he has been full professor. In 1984-1987 he served as a deputy dean of the Faculty of Law and Administration of Wrocław University, and then as a dean of that Faculty in 1987-1993. Currently, he is a professor at the Chair of Constitutional Law at Wrocław University.

He was a member of the Legislative Council of the Prime Minister from 1986 to 1988. In 1989-1991 he was a Deputy to the Sejm of the Republic of Poland where he chaired the Legislative Committee and one of the subcommittees of the Constitutional Committee.

He is a member of Committee on Legal Sciences of the Polish Academy of Sciences from 1999, and a member of the International Association of Constitutional Law. He is also a member of the Wrocław Scientific Society and Editor-in Chief of "Przegląd Sejmowy". [Sejm Review]. In 2002-2004 he was a Chairman of the Legislative Council of the Prime Minister. Since 2004 he is President of the Supreme Administrative Court.

He is an author or co-author of more than 150 scholarly publications, including 8 monographs on constitutional law.

Janusz Trzciński was a Justice and Vice-president of the Constitutional Tribunal from 1993 to 2001.