I have been watching this story with some interest and have come to the conclusion that the whole thing is a complete mess and I don't think anyone is guilty, but then by the same thought they are all guilty. I know that sounds confusing but the issue here is the way the rules and other agreements are drawn up and the fact that they are not always cross referenced.
The issue is that there is a huge team of people that get involved in the rules involving everyone from the teams, the FIA, FoM, the commercial sponsors and the bloke they pulled in off the street with the permanent drunken stare and the flea bitten dog. These rules were agreed and put into writing and everyone is happy. But, and this is a BIG but, there is a team that deals with the commercial agreements that the FIA have in place. This includes the way things are handled with the tyre suppliers, FoM, sponsorship agreements, and just about anything that means money changes hands. This team is not necessarily the same team who get involved in writing the rules, and sometimes (ok, probably most of the time) these commercial agreements are not covered by the rules and in this case fly directly in the face of the rules.
The issue is that Pirelli and Mercedes have commercial agreements in place, with the FIA and both indirectly or directly with each other. These agreements state that pirelli have the right to do certain things, and I wouldn't be surprised if the teams agreements include having to support the FIA in delivering its obligations under commercial agreements. So by the terms of the contracts they all hold with each other this test is nothing but business as usual. The problem is that the rules of the sport (which are probably referenced in both the pirelli and team commercial agreement with the FIA) state that this test is so plainly against the rules a 5 year old with a set of crayons and half a brain could underline the section in the rules they have breached.
So which should take precedence over the other? Well if it was a court of law in this country or a number of others in europe as well as the US then Pirelli and Mercedes have done nothing wrong. This comes down to the principal that any ambiguity in a contract or legal document is resolved in the favour of the person who didn't draft the document, hence as the FIA is the originator of the agreements they either have to make sure they are 100% clear or people using grey areas and loop holes will have to be let off. But unfortunately this isn't a court of law just yet and the FIA does have a way of enforcing what they want how they want it so we may end up seeing everyone found guilty and being punished.
This is all of course if the statements from various parties can be proven and are above board and correct, and some people have been having a habit of trying to muddy the waters around themselves recently so I don't think any of us can be sure we have enough information to come to any conclusion, and we probably never will have as the information will be hidden from the Tribunal report so no-one will truly know what was said in that room unless they are there...