pls help out

i want to know if there is issue estoppel or doctrine of res judicata applicable when the previous proceedings was not even an 'action' and the plaintiff was merely an intervener seeking to set aside the order for sale but in doing that he raised similar issues which he's raising now in this writ action.

I want to know which specific law guarantees a person's fundamental right to sue, and whether by estopping this plaintiff in this action, the plaintiff has been deprived of this right. kiss me I am just a dog