Suarez made another and more lasting contribution to debate on the just war. Twentieth-century Catholic just war theory has been prepared to consider that some wars might be just if they satisfy certain stringent conditions. The list of these is not fixed but is roughly the following: the war must be fought for a just cause, involving a grave injury to the state; it must be declared by a legitimate authority—in particular only states may declare war; it should be conducted by legitimate means for a limited end, in proportion to the injury; and there must be a reasonable chance of winning.
