Earl Slavitt was the lawyer present at the meeting between Claire and Arlene and Joseph Stewart. He warned Claire about the consequences of signing, such as that she would have no right to see the child at all.
Two of his pens didn't work, which Claire interpreted as a bad omen, causing her to abandon the adoption proceedings. ("Raised by Another")
Credited as "Mr. Slavitt" in the episode, his first name was revealed as Earl in the episode script.