Doctrine of Constitutional Supremacy

What is the concept of the Doctrine of Constitutional Supremacy? 

The doctrine of Constitutional Supremacy recognizes that the Constitution is the fundamental, paramount, and supreme law of the nation, and is deemed written in every statute and contract. 

If the law or contract violates any norm of the Constitution, that law or contract whether promulgated by the legislative or by the executive branch, or entered into by private persons for private purposes, shall be null and void (Manila Prince Hotel v GSIS, G.R. No. 122156, February 3, 1997). 

How is the Doctrine of Constitutional Supremacy related to the Doctrine of Separation of Powers? 

The doctrine of separation of powers provides that as a separate branch of the government, one branch should not unduly encroach on the domain of another. This rule can be attributed to the doctrine of constitutional supremacy wherein since the Constitution is the Supreme law of the land, the constitutional demarcation of the three fundamental powers of government should not be violated (Angara v. Electoral Commission G.R. No. L-45081, July 15, 1936).