Back in 2021, President Joe Biden fought hard to win Senate confirmation for Rachael Rollins to become the U.S. attorney in Massachusetts. Rollins was the district attorney of Suffolk County, which includes Boston, and she had become notorious by pledging not to prosecute many crimes. Early in her term, she published the "Rollins Memo" that listed 15 crimes in which the "default is to decline prosecuting" — that is, in which her office would not allow its attorneys to prosecute unless a supervisor gave special permission.