Reigning Premiership and European champions Saracens are facing a 35-point deduction and a £5.36m fine for breaching salary cap regulations.
The punishment, which Sarries have described as "heavy handed", is suspended while the club appeal against the decision.
Should the appeal be rejected, Saracens potentially face a battle to avoid relegation rather that challenging for more silverware.
BBC rugby union correspondent Chris Jones looks into the questions facing a club which boasts senior England players Owen Farrell, Maro Itoje and Billy and Mako Vunipola in their squad, and the potential fall-out.
What's the background?
This story revolves around Saracens' owner Nigel Wray's business co-investments with a handful of senior players, with the panel judging that the club have in essence been paying players outside the salary cap.
Wray disputes this and insists these dealings are all above board and are helping set up his players for life after rugby.
He says investment is not the same as salary. Either way, Saracens were found not to have disclosed the full details of the financial arrangements, which they have put down to an "administrative error".
How long has it been going on?
In 2015, Saracens were one of two clubs who reached confidential agreements with Premiership Rugby Limited - the league's governing body - over salary cap issues.
The league was accused at the time of turning a blind eye to any misdemeanours, and wrote the slate clean to the dismay of some clubs.
Therefore, while Saracens have been under scrutiny for a while over their management of the cap, the latest findings only apply to the last three seasons and do not take into account the investigation of 2015.
But there certainly was a widespread determination amongst others clubs and players for Saracens not to get away with it twice.
Could the club lose their titles?
As it stands, no. The punishment only applies to this season and not retrospectively. Saracens are confident they will not be losing any of their eight major titles - five Premiership crowns and three European Champions Cups - won in the past decade.
Can Saracens win their appeal?
The Premiership Rugby statement suggests Saracens' chances of a successful appeal - or review - are slim.
This has been a nine-month investigation conducted by independent legal experts, who have already considered and dismissed Saracens' defence.
So unless the review finds there has been some basic unfairness or procedural error, then it will be upheld. But at the moment the sanctions are suspended.
What will happen to Saracens' squad?
Saracens believe there will be no squad upheaval, and they won't be precluded from signing players either.
Whether they will be able to retain their young talent as well as their existing stars remains uncertain, however.
Each club did recently receive a windfall from private equity giants CVC of around £14m, which would soften the blow.
What would relegation do to Sarries?
Relegation would be catastrophic for a club that is full of England internationals - and could have a negative impact on the national side.
Going down would cause major upheaval as leading players on long-term deals consider their futures, while the commercial impact of relegation would be stark.
Saracens would, however, still retain their shares in Premiership Rugby Limited and in the process a sense of financial security.
But in the five seasons Saracens have finished as Premiership champions, a 35-point deduction would have meant them not reaching the play-offs by finishing in the top four, but would also not have seen them relegated.
They would have finished 10th last season had the same punishment been imposed.
What do rivals think?
The clubs that have spoken out publicly are fully behind the decision and the sanction.
Exeter chief executive Tony Rowe feels the panel haven't gone far enough and thinks Saracens should have been kicked out of the league.
Players at other clubs have privately expressed that view and feel Saracens' achievements and success have been tainted.
Are other clubs under scrutiny?
As it stands, there are no plans to investigate or punish any other clubs. But the severity of this decision will shine a light on the dealings of others.