The court said it expected to deliver its ruling by Tuesday morning. In its appeal, Red Bull argued that race officials should not have stripped Ricciardo of his second-place finish, and the 18 points that go with it, for breaching F1's new rules on fuel usage.
The case represented the first major challenge to this season's sweeping rule changes, which have seen F1 ditch 2.4-liter, V8 engines for smaller 1.6-liter, V6 turbo hybrid engines.
The rules are forcing teams to be more fuel efficient, allowing them to burn no more than 100 kilograms per race, about one third less than the V8s. The rules also limit the rate at which fuel is burned to no more than 100 kilograms per hour at any time.
Red Bull was accused of consistently overstepping that mark with Ricciardo's RB10 in the season-opening race on March 16. Governing body FIA told Red Bull during the race that Ricciardo was burning fuel too quickly. The team dialed back the flow for a few laps. But after that slowed Ricciardo, Red Bull then turned his engine back up again.
Red Bull argued to motorsport's Paris-based tribunal for resolving disputes, the International Court of Appeal, that the FIA-approved sensor used to measure the delivery of fuel to Ricciardo's car was faulty and so the team relied instead on its own fuel-flow measurements.
Red Bull lawyer Ali Malek said Ricciardo's sensor was "obviously unreliable," his disqualification based on a "flawed and incorrect" interpretation of F1 rules and that the team was perfectly entitled to use its own fuel calculations. He suggested the dispute was partly a teething problem.
"We are dealing with new technology, a new problem, and new regulations," he said. "It is quite plain that these fuel sensors have proved to be problematic."
Mercedes lawyer Paul Harris argued that Red Bull was knowingly in "flagrant breach" of F1 rules. He urged the court to impose an increased but suspended penalty to dissuade the team from any further violations and to keep competition fair. Restoring Ricciardo's fuel flow after the FIA asked the team to turn it down allowed him to go 0.4 seconds per lap faster, Harris claimed.
"There is a real risk that they will do it again," he said. "The most effective way of ensuring that Red Bull do not flout further written and oral instructions from the FIA for at least the remainder of this season is for this court to recognize the severity of their infringement and to impose a further sanction upon them."
Harris said that suspending the penalty for the rest of the season would make Red Bull "acutely aware" that it has no more wriggle-room.
Adrian Newey, the designer behind Red Bull's series of championship-winning cars, testified that FIA did warn the team that Ricciardo was using too much fuel, prompting them to turn it down for a few laps because "no team wants to court controversy. It doesn't want to be reported to the stewards."
But "it then became evident that if we continued to comply, despite us not agreeing with that, we would lose positions," Newey said.
The court was shown fuel-use tables which appeared to demonstrate that Red Bull turned down the flow for laps 12-17.
Much of the hearing dwelled on the accuracy and reliability of fuel sensors, how engine temperature and other factors might impact the readings, and how their accuracy compares with alternative, computer-generated fuel-flow measurements that Red Bull used.
Harris said FIA-approved fuel sensors are "rigorously tested and rigorously calibrated," while Red Bull's alternative system used for Ricciardo is "not 100 percent accurate."
"Red Bull thinks it is entitled to pick and choose between the measurements whenever it suits Red Bull," Harris said.
He also asked: If FIA allows Red Bull not to follow fuel-flow instructions, "then what is to stop a team ignoring the FIA when it comes to other measurement systems, for instance the weight of the car?"
FIA lawyer Jonathan Taylor argued that the "essence" of sport is all competitors abiding by the same rules.
"Sport can't take place in the Wild West. You have to have a set of rules that everyone accepts, a set of measurements that everyone accepts. You cannot pick and choose when you want to accept those measurements and when you don't."
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