Doctrine of State immunity from suit.
The basic postulate enshrined in the Constitution that “[t]he State may not be sued without its consent,” reflects nothing less than a recognition of the sovereign character of the State and an express affirmation of the unwritten rule effectively insulating it from the jurisdiction of courts. It is based on the very essence of sovereignty. As has been aptly observed by Justice Holmes, a sovereign is exempt from suit, not because of any formal conception or obsolete theory, but on the logical and practical ground that there can be no legal right as against the authority that makes the law on which the right depends. True, the doctrine, not too infrequently, is derisively called “the royal prerogative of dishonesty” because it grants the state the prerogative to defeat any legitimate claim against it by simply invoking its non-suability. We have had occasion to explain in its defense, however, that a continued adherence to the doctrine of non-suability cannot be deplored, for the loss of governmental efficiency and the obstacle to the performance of its multifarious functions would be far greater in severity than the inconvenience that may be caused private parties, if such fundamental principle is to be abandoned and the availability of judicial remedy is not to be accordingly restricted. (Department of Agriculture v. NLRC, 227 SCRA 693, Nov. 11, 1993 [Vitug]
Doctrine of Constitutional Supremacy
Under the doctrine of constitutional supremacy, if a 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, is null and void and without any force and effect. Thus, since the Constitution is the fundamental, paramount and supreme law of the nation, it is deemed written in every statute and contract. (Manila Prince Hotel v. GSIS, 267 SCRA 408  [Bellosillo])