Quote ="DGM"I'm not sure as to the legalities of this, but I wonder if SL clubs have the ability to add a condition into all future player contracts that stipulates the player cannot move to another sport whilst they're still under contract? Basically meaning a player can't "retire" then pop up in union a week later.'"
This is a fairly standard clause in professional sports contracts.
For example, below in a rugby union contract
[i6 PLAYER’S OBLIGATIONS
The Player shall throughout the Term of this Agreement as set out in Schedule 1:
6.1 not participate without the Club’s express written authority in any recreational sport or activity that is likely to endanger his fitness or ability to train or play rugby for the Club;
6.2 not (save where permitted pursuant to clauses 8 or 9 below) train for or play rugby union or any other competitive sport for any other club, team, body or rugby organisation otherwise than for the Club unless:
6.2.1 he shall have prior written authorisation from the Club to do so; and
6.2.2 the applicable club, team, body, organisation or union concerned shall have accepted in writing, to the satisfaction of PRL, liability for loss of salary, medical costs or other associated costs caused by any injury sustained by the Player in the course of such participation; [/i
Source, The RFU website, standard premiership rugby contract.
They governance of their sport openly allow for a clause like this to be entered into a contract. It would be difficult for them to argue that it is unenforceable if a similar clause is in Solomona's contract with Cas.