Lindsey Graham's lawyers argue that he has immunity under the US Constitution because he placed calls to Georgia's secretary of state.
The Fulton County District Attorney has been looking into efforts by former President Donald Trump and his associates to get officials in Georgia to overturn the election of Joe Biden.
Graham, a close ally of the former president, was ordered to testify before a grand jury. Rudy Giuliani was Trump's personal attorney.
Graham is accused of placing phone calls to a fellow Republican in order to get him to vote for Trump in the upcoming election.
According to The Wall Street Journal, Graham called Raffensperger and suggested that he throw out all mail-in ballots from counties with high rates of mismatches. He didn't want to. Raffensperger said that there were laws in place.
Graham insisted that he only wanted to know more about the state's election processes.
Attorneys for the senator argued that the conversations can't be subject to legal scrutiny and that the subpoena should be thrown out.
He is protected by the speech and debate clause of the constitution, which states that federal lawmakers "shall not be questioned in any other place" for their remarks during legislative sessions. The lawyers say that Graham's phone calls could be used to craft new laws.
Carol C. Lam, a former US Attorney, called Graham's response to the subpoena "disturbing" in an analysis published by NBC.
According to Roosevelt, the argument being made by Graham's attorneys is plausible.
Roosevelt said that the speech or debate clause seems to be about things that members of Congress say on the floor, but the court has read it more broadly. The question is if the court will accept Graham's characterization of his intent or if it will look at the substance of his conversations before making a decision.
The Fulton County District Attorney's office did not respond to a request for comment.