Yes, that's right, but from what I understand that's not where the problem lies. The problem is over whether the UK should keep its word and honor its treaty obligations. They approved a treaty with the EU over Brexit leaving some details on the table to be resolved, and now the Johnson government says it intends to break that treaty unilaterally. That would be a breach in international law too.We already left the EU so we should no longer be subject to their laws.