Xinis was born in Mineola, New York, graduated from the University of Virginia and went to Yale Law School. She clerked for Judge Diana Gribbon Motz on the 4th U.S. Circuit Court of Appeals. She was an assistant federal public defender in Maryland and adjunct professor at the University of Maryland Francis King Carey School of Law.

A federal judge gave the Trump administration a deadline to answer questions about Kilmar Abrego Garcia, the Maryland man whose illegal deportation has raised concerns about due process.