Fundamental law(s) may refer to:
- Organic law, in particular,
- Constitution, in particular,
- The Russian Constitution of 1906
- The German Grundgesetz (more commonly translated as "Basic Law")
- The four individual laws that together make up the Constitution of Sweden
- The Fundamental Laws of England
- The Fundamental Law of Vatican City State
- The Fundamental Law of Hungary
- The Basic Laws of a country that does not use the term "constitution" or has an uncodified constitution
- Any of the fundamental physical laws of the universe
- In Abrahmic religions, The Ten Commandments