(FORTUNE Magazine) – TV's hottest show of the moment isn't Ally McBeal, The Sopranos, or the latest prime-time cartoon on Fox. It's Judge Judy, a daytime phenomenon that has revived a moribund TV format and made a star out of a diminutive, abrasive, Jewish grandmother from Manhattan.

Now in its third season, Judge Judy has exploded into a $75-million-a-year business by attracting more viewers than Oprah, The Today Show, and everything on the fledgling WB. "She's doubled her ratings two years in a row, and I haven't seen anyone do that since Oprah," says Tim Duncan, president of Boston Media Consultants and an expert on syndicated programming. "And Judge Judy came out of nowhere."

Soon she'll be everywhere. Parodied on Saturday Night Live, profiled by 20/20, and plopped into Hollywood Squares, Judge Judy--a former family court judge named Judith Sheindlin--has written a best-selling book and signed deals for two more. Many stations run her show twice a day. In fact, Judge Judy is doing so well that a competing show, People's Court, just let go of its presiding jurist, Ed Koch, who as mayor of New York appointed Sheindlin to the bench in 1982. Koch's replacement? Judy's husband, Jerry Sheindlin, himself a judge in the Bronx. "I want him to become accustomed to the fact that No. 2 is very good," says Judy.

Besides enriching both Sheindlins, Judge Judy is making healthy profits for stations that air the program; for Big Ticket Television, which produces it; and for Worldvision Enterprises, which distributes it. Big Ticket and Worldvision are units of Viacom, whose CEO, Sumner Redstone, touts Judge Judy to analysts and investors. "She's the hottest thing going in syndication," he says.

The daughter of a Brooklyn dentist, Sheindlin, 56, took an unlikely route to TV stardom. After her no-baloney, common-sense approach to the law caught the media's attention, she wrote a book on the family courts, Don't Pee on My Leg and Tell Me It's Raining. Courtroom shows, a TV staple for decades, had disappeared from the airwaves after Judge Wapner adjourned the original People's Court for the last time in 1991. But Larry Lyttle, president of Big Ticket, figured a post-O.J. nation might be ready for a take-charge judge. More important, he took an immediate liking to Sheindlin. "She reminded me of my mother," Lyttle recalls. "But with an edge." Still, selling her to TV station owners, who are loath to take risks on unknowns, was difficult. Big Ticket and Worldvision had to give the show away, making money only by keeping control of three 30-second ad slots in each program that are then sold to advertisers. In year one, the program aired in weak time periods on weak stations and lost money.

Then the Nielsen jury rendered its verdict. Viewers flocked to Judge Judy, who, unlike real-life judges, speaks plainly and disposes of cases in tidy 12-minute segments. The disputes are usually mundane--unpaid loans, dinged cars, relationships gone sour--but the payoff comes when she lectures litigants on everything from good behavior to proper grooming. A typical example: "You both acted like idiots," she scolded one pair of disputants on a recent show.

Thirty-second spots in Judge Judy now sell for about $85,000, up from less than $10,000 when the show first went on the air. License fees have climbed even faster. In New York City, Judge Judy moved from WOR-TV, a second-rate outlet owned by Chris-Craft, which got the show free, to CBS's WCBS-TV, where she boosted ratings for local news. Next fall the show moves to NBC's top-ranked WNBC-TV, which snatched it away from CBS by agreeing to pay more than $125,000 a week. Meanwhile, the costs of producing Judge Judy are only about $250,000 a week, less than half the cost of making a network-sitcom episode--although Sheindlin recently bargained for a fat raise that will cut into Viacom's profits.

This being television, Judge Judy has spawned a raft of imitators. Besides her husband, Jerry, on the new People's Court, the competition includes Judge Joe Brown (who still sits on a real bench in Nashville), Judge Mills Lane (the boxing referee), next fall's revival of Divorce Court, and a new show built around a young Detroit judge named Greg Mathis. Even Judge Wapner is back--on cable's Animal Planet, this time presiding over Animal Court.

--Marc Gunther