Context: According to the preamble in The Law of Treaties, treaties are a source of international law. If an act or lack thereof is condemned under international law, the act will not assume international legality even if approved by internal law. This means that in case of a conflict with domestic law, international law will always prevail.

Question: The preamble of what states that treaties are a source of international law?
Answer: The Law of Treaties

Question: Which will prevail in a conflict between international and domestic law?
Answer: international law

Question: What are started to be a source of international law in the preamble in The Law of Treaties?
Answer: treaties

Question: Approval under what law will not make an act or lack thereof legal if condemned under international law?
Answer: internal law

Question: An act or lack thereof cannot be made legal under what law even if made legal under internal law?
Answer: international law