LOS ANGELES — To use a phrase from “Who Wants to Be a Millionaire,” the game show handed ABC a lifeline.

Now the network could be on the hook.

The Walt Disney Co.-owned network had been trailing in the ratings in the summer of 1999 when “Millionaire” premiered, offering a $1 million prize for the contestant who could answer increasingly challenging questions.

“Millionaire” was an overnight sensation — and would become ABC’s first top-rated prime-time show in more than a decade. Former Disney Chief Executive Michael Eisner proclaimed it “the most important thing to happen to ABC since I don’t know when.”

As big a hit as “Millionaire” was for ABC — the network at one point slapped it on the air five nights a week — the one thing the British import didn’t do was make a profit for its creator, according to a lawsuit and trial under way in Riverside County, Calif., that is seeking up to $395 million in damages.

The legal battle over “Millionaire” is the latest case of what is derisively called “Hollywood accounting,” in which TV shows that become monster hits, mysteriously, never earn a dime. These disputes became increasingly frequent after a wave of media consolidation that brought buyers and sellers of television programming under the same corporate umbrella.

A jury is scheduled today to enter its third day of deliberations in what could turn out, if the plaintiff prevails, to be a setback in the raison d’etre behind the media giants: the merger of program production with program distribution.

The legal wrangling began six years ago, when the creator of “Millionaire,” Celador International Ltd., sued Disney, ABC and two affiliated companies involved in producing and distributing the show. Celador alleges a series of “sweetheart deals” took place among a clutch of Disney companies that allowed ABC to pay below-market rates for the hit show, while depriving Celador of millions in potential profit.

Roman Silberfeld, a lawyer for Celador, said “Millionaire” generated $515 million in revenue from license fees for its run in prime time starring Regis Philbin on ABC and in new episodes starring Meredith Vieira for TV stations over the past eight years, not including $70 million in merchandising revenue.

According to Disney’s accounting, “Millionaire,” now on the air more than a decade, has run a $73 million deficit.