Robert E. Morin, a longtime defense lawyer who specialized in death-penalty cases, took office Friday as the newest judge on the D.C. Superior Court.

Morin, 43, replaces Curtis E. von Kaan, who left the bench last year to return to private practice. As his first assignment, Morin will handle criminal misdemeanor cases.

For the last 10 years, Morin was a partner in the firm of Fisher, Morin and Hansen. His clients there included Kirk N. Bloodsworth, an Eastern Shore waterman who was freed from prison in 1993 after DNA evidence cleared him of the 1984 rape and slaying of a 9-year-old suburban Baltimore girl.

Morin's work on the Bloodsworth case contributed to his selection as 1993 Lawyer of the Year by the Maryland Association of Criminal Defense Attorneys and the District of Columbia Association of Criminal Defense Lawyers.

Morin has a long history of defending people in what seemed to be hopeless cases. In 1982, he helped establish the Southern Center for Human Rights in Atlanta, which represents indigent people facing the death penalty. Two years later, he became a public defender in Maryland, again handling capital cases.

In addition to his private practice, Morin has taught since 1986 at Georgetown University Law Center. He also does volunteer work for the Rosemount Bilingual Education Center and Oyster Bilingual Elementary School. Morin and his wife, Martha Tomich, have two children, Kristopher, 8, and Willem, 6. CAPTION: Judge Robert E. Morin will handle criminal misdemeanor cases.