There is an actual ruleThe Premier League rule that would give the “Other 14” the greatest chance to prevent the ESL breakaway would appear to be Rule L9. Here it is:
“Except with the prior written approval of the board, during the season a club shall not enter or play its senior men’s first team in any competition other than:
L.9.1 - The UEFA Champions League
L.9.2 - The UEFA Europa League
L.9.3 - The FA Cup
L.9.4 - The FA Community Shield
L.9.5 - The Football League Cup or
L.9.6 - Competitions sanctioned by the County Association of which it is a member.”
As you can see, “Lucrative European Super League” is not on that list.
Now let's see if they have the balls to punish them.