Ill. R. Evid. 501
As amended through September 23, 2024
Except as otherwise required by the Constitution of the United States, the Constitution of Illinois, or provided by applicable statute or rule prescribed by the Supreme Court, the privilege of a witness, person, government, state, or political subdivision thereof shall be governed by the principles of the common law as they may be interpreted by Illinois courts in the light of reason and experience.
Ill. R. Evid. 501