It feels as if we have been waiting for ever for another legal ruling that would not only change the face of football but be synonymous with a single professional player. At long last we might have a new Bosman. The verdict delivered by the court of justice of the European Union (CJEU) on Friday – AKA the Lassana Diarra ruling – will almost certainly lead to significant change in the game.

This legal process, which started nine years ago, is still not finished. Ultimately, it will be up to Belgian courts to rule whether key Fifa laws relating to the transfer market are a going concern. But given these final considerations must be made within the jurisdiction of EU law, and that the EU’s top court has said that Fifa’s rules “in several respects go beyond … in some cases well beyond … what is necessary”, we can assume that the status quo may well be on its last legs.

Ostensibly, the case relates to what happens when a player’s contract is terminated “without just cause”. This is what happened to Diarra in 2014, when he was playing for Lokomotiv Moscow. A dispute over performance and wages led to his contract being cancelled by the Russian club, with Fifa’s dispute and resolution chamber (DRC) finding against the former France midfielder and subsequently fining him.

When Diarra subsequently struck a new deal with the Belgian club Charleroi, he was unable to complete the move because a transfer permit would not be granted until the fine was paid. Furthermore, Charleroi would have been held liable for that debt had they sought to finalise a deal and potentially punished if they refused to pay it. This was an outcome the Belgian club decided they could not risk and, therefore, walked away from the deal. From this situation the CJEU was asked to consider two details: first, whether the refusal of a permit restricted Diarra’s freedom of movement, and second, whether the obligations placed on Charleroi, and the potential for punishment, restricted their ability to compete.

On both these issues the court ruled against Fifa. Even the world governing body’s defence that such rules were necessary in order to “ensure the regularity of sporting competitions” were seen as insufficient because the court found the rules “go beyond what is necessary to achieve that objective”.

Fifa now has one final chance to argue differently when it makes its their case to the Belgian appeal court where this case is being heard. The CJEU says the plea will have to be convincing. “An exemption [is possible] only if it is demonstrated, by means of convincing arguments and evidence, that all the conditions required for that purpose are met,” it argued in the judgment.

The outcomes will not be immediate, but it seems that Fifa’s initial response, that this ruling was small beer and that “questions remained only over two paragraphs of two articles of the Fifa regulations”, does not quite capture the scale of possibilities. To start with, it seems far more likely that players will be able to walk away from their contracts thanks to this ruling. It also seems likely that rules that determine who is owed compensation and how much in the event of a “without just cause” break-up will have to change, as the CJEU says “such compensation criteria seem more intended to protect the financial interests of clubs … than to ensure the supposed smooth running of sporting competitions”. It also seems likely that the financial liabilities on buying clubs will change, too, away from an assumption that they are somehow responsible for the move, quite possibly to the opposite conclusion.

These are all substantial changes that are interlocked and will probably have unintended consequences, however they are resolved. But they are not the only things at stake for Fifa and other governing bodies as a result of this ruling.

Dupont-Hissel, the legal firm representing Diarra who just happened to also be Jean-Marc Bosman’s lawyers, immediately responded to the verdict by saying that it was a “total victory” for Diarra, one that affected “all professional players” going back to 2001 and which would allow them to “seek compensation for their losses”, presumably those that came from being unable to rip up their contract and move to a club that paid them better. So yet more legal action incoming.

But more than that there is renewed scrutiny on Fifa as a rule maker. The Super League case last year led to an outcome whereby Uefa was told it had to be more accountable and its rule making more transparent. That case is cited several times in the Diarra judgment, which could be seen as following on from it. Not only are questions raised here as to whether Fifa’s rules are fair and their provisions proportionate, the judgment makes reference to the “uncertainty” or “lack of certainty” caused by the same rules, implying, at the very least, that they need to be rewritten for greater clarity.

This, as it happens, is in line with the sentiment held by players’ unions over a number of issues. Dupont-Hissel has been hired by Fifpro, the global union, to represent it in a case it is bringing against Fifa over the upcoming Club World Cup, arguing the plans violate EU laws on workers’ welfare. On Friday, the chief executive of the Professional Footballers’ Association, Maheta Molango, himself a successful sports lawyer, said the Diarra ruling made a broader point, “demonstrating again that football cannot behave like it does not have to work within the same employment laws that apply to any other industry”. Football authorities, Molango added, “need to be making an honest and open assessment of the suitability of their rules and how they sit alongside employment laws. They then need to start making genuine and proactive efforts to work with players and their unions.”

Root and branch reform of the entire system of governance remains unlikely. But this ruling certainly makes it more possible, and it is hard not to conclude that it has the potential to alter the balance of power in professional football.