UEFA's reliance on evidence first uncovered by Football Leaks could have been key to the outcome of Manchester City's Court of Arbitration for Sport appeal, according to a sports law expert.

The Premier League club had a two-year ban from UEFA competitions overturned on Monday, after CAS concluded they did not disguise equity funding as sponsorship contributions.

City were fined €10million – down from €30m – for failing to cooperate with the initial investigation, which saw them found guilty of breaching Financial Fair Play rules by European football's governing body.

However, CAS concluded that the alleged breaches were "not established or time-barred" – the latter element referring to UEFA's own rulebook that states claimed irregularities from more than five years ago are not admissible for punishment.

UEFA's latest investigation into City, who they fined for falling foul of FFP regulations in May 2014, stemmed from a series of reports by Der Spiegel, the German publication that drew on documents obtained by the whistleblower Football Leaks, purportedly showing funds from sponsors linked to the club's Abu Dhabi ownership had been improperly topped up.

Richard Cramer of Front Row Legal, a specialist in sports law, feels UEFA's reliance on those findings is likely to have been seized upon by City's legal team.

"We're waiting for the full verdict, so it's a little bit premature to be critical of UEFA or Manchester City," he told Stats Perform News. "What we do know is that this has been an ongoing matter since 2014.

"I would imagine the thrust of the submissions made by Manchester City, who had probably the finest legal brains in the country representing them, is that [Football Leaks] evidence is regarded as tainted because someone hacked into [City's] IT system."

While Pep Guardiola can call upon the midfield mastery of Kevin De Bruyne on the pitch, Cramer explained City's owners had their own courtroom superstar when it came to taking on UEFA in the form of Lord David Pannick QC.

Lord Pannick led the Supreme Court Article 50 case that Gina Miller brought against the UK government in relation to its Brexit policy and is highly respected in legal circles.

"Manchester City were able – and not every club can do this – to appoint probably the finest legal brains this country has got," Cramer reiterated.

"They brought out the golden boy, which was David Pannick QC.

"David Pannick is a very safe pair of hands, highly eminent and has clearly understood the issues. Him and the team around him have produced a magnificent result."

What that result means for UEFA is not immediately clear.

In a statement after the verdict, the organisation underlined its commitment to the principles of FFP, although further tweaks to a model first introduced in 2009 are to be expected.

While acknowledging the decision will hurt in Nyon, Cramer does not expect any further legal recourse – which in this instance would come with an appeal to the Swiss Federal Tribunal.

"It would have been difficult for Manchester City to take the matter to the Swiss Federal Court," he said. "Similarly, I think it's difficult for UEFA to appeal that decision.

"The only basis upon which either party has got grounds to take this further is if there have been procedural irregularities in the Court of Arbitration for Sport's proceedings, or the decision is perverse or capricious.

"UEFA will be licking their wounds and considering with their lawyers whether there is another avenue, but there's also an element that will probably say 'enough is enough' and to create further uncertainty hanging over the club isn't good.

"I suspect they'll probably throw the towel in and just take it on the chin."