Whoever said lawyers are humorless and one-dimensional has not heard Jay Rosenthal's composition "Advocat's Blues."

Rosenthal, a copyright officer at the Library of Congress, will demonstrate not only his humor but his prowess on the piano when he performs with his sister-in-law, singer Beth Wasserman, at Glen Echo Park today at 2:30.

The program will include jazz and folk ballads, show tunes and occasional humor pieces.

"If I had to label myself, I would say that I am in the Randy Newman, Arlo Guthrie and Tom Waites genre," says Rosenthal, 27. "I like to perform a variety of different music and also to poke fun. I also have a strong interest in politics and law. I hope to combine these two interests and work in the field of entertainment law and concert management."

While a student at American University, Rosenthal managed coffee houses and was the opening act for Chris Smither when he appeared on campus. Later he played with the Willie Nininger band at the Cellar Door, and currently functions as Nininger's Washington agent.

Rosenthal and Wasserman appear in the first of a series of four concerts coordinated by the Bethesda Co-Op and Glen Echo Park. These concerts provide a commercial outlet to musicians who might otherwise not have such a forum. The concerts will run each Sunday in January and feature a variety of musical styles from American folk songs to Renaissance and Baroque pieces to country blues.