If it can be shown that one of the parties was in the presence of one of the contracting parties, the treaty cannot be enforceable. The EU has always hesitated to act when there is a democratic backsliding, it has previously hidden behind the fact that Article 7 does not work and that it does not have the right toolbox, so try to create new mechanisms. The problem with this new agreement is that any mechanism that Hungary and Poland vote for will also be watered down and, in reality, unenforceable. What made you not apply it? Please let us know where you read or heard it (including the quote, if possible). To challenge a treaty is to attack the integrity of the treaty. One way to do this is to treat the treaty as unenforceable. A contract may be considered unenforceable if it is contrary to the legislation on fraud or the law on the movement of goods.