Microsoft announced sweeping changes 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. 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. Smith said that Microsoft would make sure that it was no longer offering legal support to politically motivated piracy inquiries by providing a blanket software license to advocacy groups and media outlets. They would be automatically covered by it, without having to apply. Advocates and journalists who have been targets of such raids said they were pleased that Microsoft was announcing reforms, although some added that they remained suspicious of its intentions. The piracy cases have stirred resentment toward Microsoft in the nonprofit sector in Russia. In his statement, Smith appeared to acknowledge that Microsoft needed to address the damage to its image. He said the company would set up a program to offer legal aid to nonprofit groups and media outlets in Russia that are caught up in software inquiries. He also said the company had retained an international law firm to investigate its operations in the country. 