Mercedes say the arrangements for their controversial Pirelli tyre test were based on "privacy not secrecy".
Mercedes and Pirelli will appear before F1's international tribunal after governing body the FIA said it "may constitute a breach" of F1's rules.
Mercedes team boss Ross Brawn told BBC Sport: "It was a Pirelli test. What we were seeking was privacy not secrecy.
"You don't go testing in Barcelona for three days and expect people not to know about it."
"It was a Pirelli test. What we were seeking was privacy not secrecy."
Mercedes team boss Ross Brawn
The process that has ended with
Mercedes and Pirelli facing charges
over the test started with a
protest by Ferrari and Red Bull
at the Monaco Grand Prix two weeks ago.
Rivals are incensed that Mercedes used a 2013 car for the test, which is illegal according to the sporting regulations.
Neither Pirelli nor Mercedes told the other teams about the test, which took place for three days starting on the Wednesday after the Spanish Grand Prix, and drivers Lewis Hamilton and Nico Rosberg wore non-identifiable helmets.
Brawn, talking in an exclusive interview with BBC chief F1 analyst Eddie Jordan, said: "It was a Pirelli test, on the Wednesday to Friday after the race. It couldn't be held any closer to the weekend because people were packing up.
"On the Tuesday there were still motorhomes being dissembled, garages being taken apart, and there we were in our full regalia with the trucks and the Pirelli trucks and everything. There was no secrecy involved; it was privacy.
"The reason for the drivers' helmets is it was a Pirelli test, they organised the security, they organised all the arrangements.
"We didn't want to bring attention to the drivers, we didn't want to have to put security there, we didn't want to have to put minders.
"The easiest way for us was to not bring attention to what drivers were in the car, only for those reasons. We have always been very open about the drivers.
"The drivers are irrelevant - there's nothing in the sporting regulations, nothing in the arrangements for these tests that controls which drivers are in the car.
"There was no issue there. It was purely privacy and nothing more."
"My conscience is clear," he added.
Asked why the other teams had not been informed, Brawn said: "It was a Pirelli test, we don't believe we had an obligation to inform other teams, if Pirelli wanted to inform other teams that's up to them.
"We're comfortable it was a Pirelli test requested by Pirelli. It's for Pirelli to decide what they want to do with it."
Pirelli has a contract with the FIA that allows it to do tests of up to 1,000km to develop tyres.
The tyre company had asked the FIA a general question about whether it was possible to run a 2013 car in such circumstances, but had not gone back to ask for specific permission for this test.
It is understood their failure to do that and to inform the other teams may have left them in breach of contract.
Asked to clarify comments from Rosberg that he knew what tyres he was using, Brawn insisted Mercedes had not learned anything from the test, which he said was run by Pirelli.
He admitted the drivers "had some awareness of the tyres but that's the awareness you have to give a driver if tyre testing.
"If you want to be effective in testing you have to give the driver some guidance of what you are looking for. It wasn't: 'This is the tyre we're using at the next race.'
"Pirelli are building a jigsaw. We don't know what is what. But it would be irresponsible to put a tyre on the car without giving the driver a bit of guidance of what it is, a new construction or whatever, and that's what we want you to look for."
Pirelli has said "about 90%" of the test was focused on 2014 and the rest on a new type of tyre that they hope to introduce from the British Grand Prix. The teams have examples of the new tyre to test in practice at the Canadian Grand Prix on Friday.
Brawn said it was important for Pirelli to do the test because it needed to prepare tyres for next season, when the cars will be significantly different following a change in the chassis and engine regulations.
And he said it was wrong for people to make judgements about the legality of the test before they knew the full facts.
He said: "Sporting integrity is vital to Mercedes. It would be easy for me to challenge that.
"When we get to the international tribunal and everything's explained, people can make a judgement when they know the facts. I'm not going to pre-empt those facts. It's unfortunate to be making judgements before the facts are known."
Asked about his feelings about Mercedes' chances at the tribunal, Brawn said: "This is a new process the FIA have introduced. We all had criticisms of the process in the past. No one was particularly comfortable with it.
"It's independent. Independent judges will sit. I'm optimistic once the facts are presented they will see things the way we see them."
No date has been announced for the international tribunal hearing.