Cook County State’s attorney Anita Alvarez is in Washington D.C. Monday preparing to argue her first case before the U.S. Supreme Court.

The case stems from a rape in 2000 that was prosecuted by the Cook County State’s Attorney’s office. There was DNA evidence, but the forensic expert who testified about it for the prosecution wasn’t the expert who actually tested and wrote the report on the DNA. The defendant Sandy Williams says that deprived him of his constitutional right to confront his accusers. But prosecutors argue that scientists often rely on DNA data produced by other scientists.

According to a spokeswoman for the state’s attorney, the case would normally be handled by the office’s appeals division and Alvarez has been working with them. Three of her four children and her husband plan to attend the argument scheduled for Tuesday.