"the royal prerogative of dishonesty";par in parem, non habet imperium.

The rule that a state may not be sued without its consent, now expressed in Article XVI, Section 3, of the 1987 Constitution, is one of the generally accepted principles of international law that we have adopted as part of the law of our land under Article II, Section 2. This latter provision merely reiterates a policy earlier embodied in the 1935 and 1973 Constitutions and also intended to manifest our resolve to abide by the rules of the international community.

Even without such affirmation, we would still be bound by the generally accepted principles of international law under the doctrine of incorporation. Under this doctrine, as accepted by the majority of states, such principles are deemed incorporated in the law of every civilized state as a condition and consequence of its membership in the society of nations. Upon its admission to such society, the state is automatically obligated to comply with these principles in its relations with other states.

As applied to the local state, the doctrine of state immunity is based on the justification given by Justice Holmes that "there can be no legal right against the authority which makes the law on which the right depends."^[12]  There are other practical reasons for the enforcement of the doctrine. In the case of the foreign state sought to be impleaded in the local jurisdiction, the added inhibition is expressed in the maxim par in parem, non habet imperium. All states are sovereign equals and cannot assert jurisdiction over one another. A contrary disposition would, in the language of a celebrated case, "unduly vex the peace of nations."^[13]

While the doctrine appears to prohibit only suits against the state without its consent, it is also applicable to complaints filed against officials of the state for acts allegedly performed by them in the discharge of their duties. The rule is that if the judgment against such officials will require the state itself to perform an affirmative act to satisfy the same, such as the appropriation of the amount needed to pay the damages awarded against them, the suit must be regarded as against the state itself although it has not been formally impleaded.^[14] In such a situation, the state may move to dismiss the complaint on the ground that it has been filed without its consent.

The doctrine is sometimes derisively called "the royal prerogative of dishonesty" because of the privilege it grants the state to defeat any legitimate claim against it by simply invoking its non-suability. That is hardly fair, at least in democratic societies, for the state is not an unfeeling tyrant unmoved by the valid claims of its citizens. In fact, the doctrine is not absolute and does not say the state may not be sued under any circumstance. On the contrary, the rule says that the state may not be sued without its consent, which clearly imports that it may be sued if it consents.

The consent of the state to be sued may be manifested expressly or impliedly. Express consent may be embodied in a general law or a special law. Consent is implied when the state enters into a contract or it itself commences litigation.

The general law waiving the immunity of the state from suit is found in Act No. 3083, under which the Philippine government "consents and submits to be sued upon any moneyed claim involving liability arising from contract, express or implied, which could serve as a basis of civil action between private parties." In Merritt v. Government of the Philippine Islands,^[15] a special law was passed to enable a person to sue the government for an alleged tort. When the government enters into a contract, it is deemed to have descended to the level of the other contracting party and divested of its sovereign immunity from suit with its implied consent.^[16] Waiver is also implied when the government files a complaint, thus opening itself to a counterclaim.^[17]

The above rules are subject to qualification. Express consent is effected only by the will of the legislature through the medium of a duly enacted statute.^[18] We have held that not all contracts entered into by the government will operate as a waiver of its non-suability; distinction must be made between its sovereign and proprietary acts.^[19] As for the filing of a complaint by the government, suability will result only where the government is claiming affirmative relief from the defendant.^[20]