Articles 46–53 of the Vienna Convention on the Law of Treaties set out the only ways that treaties can be invalidated—considered unenforceable and void under international law. A treaty will be invalidated due to either the circumstances by which a state party joined the treaty, or due to <answer>the content of the treaty itself</answer>. Invalidation is separate from withdrawal, suspension, or termination (addressed above), which all involve an alteration in the consent of the parties of a previously valid treaty rather than the invalidation of that consent in the first place.
In addition to the circumstances by which a state party joined a treaty, why might a treaty be invalidated?
the content of the treaty itself