During the team's testimony at the FIA headquarters in Paris on Thursday, Mercedes' lawyer Paul Harris QC claimed that if the International Tribunal adopts a strict interpretation of the testing rules, then Ferrari would also have to be in the wrong even though it ran its 2011 car.
Ferrari took part in a Pirelli tyre test at Barcelona ahead of the Spanish Grand Prix using a two-year-old car with its test driver Pedro de la Rosa.
Although it has been accepted by the FIA that running two-year-old cars is permissible, Harris argues that a strict interpretation of article 22 says that cars cannot 'conform substantially' with the current rules.
Article 22 defines testing as: "Any track running time not part of an event undertaken by a competitor entered in the championship, using cars which conform substantially with the current Formula 1 technical regulations in addition to those from the previous or subsequent year."
Harris said: "Our position is if we are wrong on interpretation of what [article] 22 means and there was track running by us, such as we are in breach, it follows that Ferrari were also in breach.
"They ran their car on track and we argue their car followed substantially with the regulations... I put the marker down.
"It does not follow that if Ferrari runs on track a 2011 car, that that 2011 car does not confirm substantially to either the 2012 or 2013 regulations.
"There was only half [a second] difference between the 2011 cars and 2013 cars, showing the changes between 2011 and 2013 are minuscule in terms of performance."
Mercedes also revealed that Ferrari had another testing opportunity in 2012 with Pirelli, when Felipe Massa was used in its pre-Spanish Grand Prix test and that the team conducted more than 1000 kilometres.
Harris also added that if Ferrari was not deemed to be in breach of article 151C for conducting its 2011 car test, then Mercedes could not be either for running a 2013 contender.
"We note the same lack of transparency being held against us is identical compared to the lack of transparency with both Ferrari tests," he said.
Harris argued that Ferrari also conducted non-Pirelli specific testing during the Barcelona test, which was booked and paid for by the team itself rather than the tyre supplier.
He cited a run sheet from the Barcelona test that showed it conducting 'balance tests' in the middle of the day.
Furthermore, he revealed that there was correspondence between Ferrari tyre engineer Hirohide Hamashima and Pirelli on May 3, after the test, talking about details of Pirelli data from the runs.