One of his greatest successes came recently, when he used the act to help solve a homicide case that had lain dormant for months. Based on information Mr. Kalayansundaram received through an information request, the police were able to identify a suspect.

Mr. Kalayansundaram emphasized that his efforts have not always gone smoothly. He talked of recalcitrant officials who held up requests for information and of the death threats he had received. Some opponents had put up posters around his house questioning his sources of income and accusing him of illegal activity.

Still, his overall sense was that the law was improving governance. “All the officials are scared of R.T.I. now,” he said, speaking of the information act. “They move more quickly. If they don’t answer within 30 days, they know they can be suspended.”

One of the chief benefits of the law, Mr. Kalayansundaram said, is that it confers something of an administrative weapon that responsive officials can use against less responsive colleagues. It permits, in effect, what the political scientist Pratap Bhanu Mehta called “institutional competition,” a way for different branches of government to maintain oversight over each other, which is an essential component of good governance.

Using the information act, for example, a person can provide information to a judge that allows the judiciary to challenge police inaction. Likewise, the law permits honest officials to act on information collected by citizens against corrupt officials in their own department.

Over the years, the act has been hailed as revolutionary and emancipatory. Last year, President Pratibha Patil said that it had “created a virtual Parliament of People.”

Such praise seems to be borne out by the many stories of people across the country using the act to uncover corruption and improve public services. According to a recent survey conducted by a coalition of civil society groups, more than two million information requests were filed in the first two and a half years after the law’s inception.