(FORTUNE Magazine) – No man wields more power over any industry than Judge Harold H. Greene of the U.S. district court in Washington, D.C. He transformed the telecommunications business by approving the breakup of AT&T and now oversees the post- divestiture rules. Says William Baxter, chief prosecutor of the antitrust case: ''Under another judge the entire industry might be very different today.'' Critics ask why a single person should hold such sway. Interviewed by Fortune's Kate Ballen, Judge Greene, 65, answers his detractors -- and offers some personal insights:

Are you surprised that you are still so involved in the telephone system? Yes. I thought once the decree was entered, there might be a little bit of controversy here and there, requests for this and that, but not on the constant basis there has been. Since the breakup I've probably received over 1,000 briefs because all the phone companies are constantly filing requests for enforcement and interpretation.

Is divestiture a success? The main purpose of the decree was to bring competition into the telecommunications industry by way of reduced rates and more innovation, yet to keep the quality of the network at least as high as it was before. The divestiture has been very successful on all these fronts. In my opinion the most significant consequence has been the increase in innovations. It has been said that if GE had acted in the last 40 years as AT&T did, the American consumer would have the most durable light bulb in the world but no dryers and dishwashers.

Will you ever allow the regional companies into long distance, manufacturing, and information services? The decree says that the restrictions should be lifted only when the regionals cannot use their monopolistic power to impede competition in markets they want to enter. That day has not yet arrived. Unless, of course, you assume the addition of a wolf to a flock of sheep would maximize competition in the flock.

The Justice Department, the regionals, and the Federal Communications Commission would like to give all control of the industry back to the FCC. How would you feel about this? When outside forces come along and say we want to do what is the court's business, I obviously don't think that's a good idea. The decree was drafted by AT&T and Justice. I approved it, and the Supreme Court upheld my decision. This was a legitimate lawsuit. I've made it clear that any interested party can file on my decisions. Obviously the expectations of those people who want to transfer the power to the FCC or elsewhere figure that they would eliminate the restrictions or not enforce what I would.

Which company did you choose as your long-distance carrier? I deliberately did not pick a long-distance carrier because I felt my choice could be used commercially in advertising. I waited for a carrier to be assigned -- and it happened to be AT&T.