State attorney general Dan Morales asked a state district court in Austin's Travis County today to prohibit the company from "undermining the state's investigation into possible antitrust violations by the company."
According to the suit, "Microsoft requires all companies with which it does business to sign a contract requiring the companies to inform Microsoft prior to providing any information to state or federal antitrust investigators."
Today's lawsuit follows last month's charges by the Justice Department that Microsoft had violated a 1995 consent decree governing its licensing practices. Critics have accused the company of strong-arming computer makers into accepting the terms of its deals.
Microsoft could not immediately be reached for comment.
Morales's suit said the company has interfered with the state's "constitutional and statutory responsibilities to conduct unobstructed confidential investigations."