Following a morning of fascinating submissions put forward by both the FIA and Mercedes in relation to the contentious three-day Barcelona test, F1's tire supplier took the stand in the afternoon to put across their side of the story.
All eyes had been on how Pirelli would approach the hearing and respond to their charges given they are a supplier, rather than an F1 competitor, and their lawyer Dominique Dumas immediately made clear that "we do not come under the jurisdiction or authority of the FIA".
Indeed, Dumas cited the FIA's 2009 'Crashgate' case involving former Renault team boss Flavio Briatore as evidence of how the FIA have no power to discipline a third party, Briatore having later had his ban overturned in the French civil courts prior to the governing body introducing licenses for team personnel.
During the morning session the FIA's lawyers had argued that although Pirelli's contract with them permitted up to 1000km of testing with any of the teams, the deal also stipulated that they are bound to the FIA's own Sporting Regulations as well, which forbid in-season testing with a current car.
However, as part of Pirelli's defense case, Dumas argued that their FIA contract contained no restrictions about what car can be used for the firm's permitted F1 tests.
Responding to Pirelli's submissions, the FIA's QC Mark Howard claimed the tire firm's statements "are confused and miss the point" with the governing body adamant that both the Italian supplier and Mercedes have breached the sporting regulations.
Reporting direct from outside the Tribunal, Sky Sports News' Craig Slater added: "They [the FIA] say that Pirelli's contract is subject to the Sporting Regulations and they can't be ignored, especially if they are involved with a current team. [According to the FIA], it is one thing for Pirelli to test tires, but quite another to involve an entrant – and if they do that, it is effectively an in-season test, which is banned.' Sky Sports
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But also at the FIA's Place de la Concorde headquarters were representatives of McLaren and Williams, as the governing body's lawyer clearly accused Mercedes of breaking the rules with its highly controversial Barcelona test last month.
"Any running on the track is deemed to be testing," the FIA's lawyer said.
"It is difficult to say that Mercedes gained no benefit," he added.
The FIA also alleged that Mercedes and Pirelli were "very odd" in how they went about seeking permission to test, having made "informal" calls and emails to Charlie Whiting and the governing body's legal department, but then going ahead with the test without obtaining clear answers.
Mercedes' lawyer hit back by arguing the Brackley based team did not actually break the rules, because the sporting regulations say only that a team may not 'undertake' a test.
"It is irrefutable it was a test undertaken by Pirelli," he said.
The Mercedes lawyer also accused Ferrari of doing more than 1000 kilometers of testing in the weeks before the Barcelona session, while admitting that having Lewis Hamilton and Nico Rosberg wear all-black helmets was a "regrettable" decision.
"We acknowledge this aspect was bound to raise suspicion," he acknowledged.
A bullish Pirelli, meanwhile, argued that it fully complied with its contract with the FIA, and insisted it cannot be punished because it is not a team or driver.