The US literally passed a law allowing itself to invade The Hague if necessary to free any US service member brought before the International Court of Justice. Even the signatories of the UN human rights conventions could simply refuse to cooperate and experience no meaningful consequences. International laws are just treaties and treaties can be cancelled or revoked. Human rights are no more reliable than company mission statements.
Not to mention that even on a national level laws only exist as limitations the state imposes on itself (or to chisel away at limitations it imposed on itself before). This is why it took the civil rights protests and literal terrorism to arrive at universal suffrage and civil rights for women and Black people. Of course this only works if the government would rather change its laws than escalate protests to a civil war and which one your government chooses might surprise you.