A federal judge in California will hear arguments on Tuesday about whether to grant discovery involving evidence allegedly indicating the U.S. Department of Justice filed its $5 billion lawsuit against Standard & Poor’s Financial Services LLC in retaliation for its downgraded credit rating of the United States.

S&P, the only ratings agency that downgraded the country’s credit rating during one of its debt-ceiling crises—and the only agency the Justice Department sued over its valuation of mortgage-backed securities—has argued that the suit violates its First Amendment free speech rights.