MOSCOW  Microsoft announced sweeping changes on Monday to ensure that the authorities in Russia and elsewhere do not use crackdowns on software piracy as an excuse to suppress advocacy or opposition groups, effectively prohibiting its lawyers from taking part in such cases.

The company was responding to criticism that it had supported tactics to clamp down on dissent.

The security services in Russia in recent years have seized computers from dozens of outspoken advocacy groups and opposition newspapers, all but disabling them. Law-enforcement officials claim that they are investigating the theft of Microsoft’s intellectual property, but the searches typically happen when those groups are seeking to draw attention to a cause or an event. Allies of the government are rarely if ever investigated for having illegal software on their computers.

The raids have turned into a potent tool to muzzle opposition voices, and private lawyers retained by Microsoft have often bolstered the accusations, asserting that the company was a victim and calling for criminal charges. Until Monday, the company had rebuffed pleas from Russia’s leading human-rights organizations that it refrain from involvement in these cases, saying that it was merely complying with Russian law.

The new Microsoft policy was announced in an apologetic statement by the company’s senior vice president and general counsel, Brad Smith, issued from its headquarters in Redmond, Wash. His statement followed an article in The New York Times on Sunday that detailed piracy cases against prominent advocacy groups and newspapers, including one of Russia’s most influential environmental groups.