https://www.npr.org/2022/11/01/ [login to see] /supreme-court-lindsey-graham-grand-jury-georgia
The Supreme Court said Tuesday that Sen. Lindsey Graham, R-S.C., must testify before a grand jury in Georgia. He has been subpoenaed for questioning later this month about allegations that then President Donald Trump tried to interfere with Georgia's ballot count after the 2020 election.
Graham filed an emergency request to block the subpoena late last month. Under the Constitution's "Speech or Debate" clause, sitting senators may not be "questioned" about their legislative activity, which protects them from civil and criminal liability in certain circumstances. The purpose of the clause is to shield legislators from unwarranted intrusions on their duties by other branches of government.
Graham argued that the actions he took following the election, which included phone calls to Georgia election officials, were legislative in nature – related to his role as then-chair of the Senate Judiciary Committee. Therefore, he said, he cannot be called to testify about these actions, even just as a witness. He further argued that the principle of "sovereign immunity" shields him from subpoena.