Measure for Measure begins with the Duke of Vienna apparently giving up power and vesting it in his deputy, Angelo, stressing that he will have complete authority to do everything the Duke himself could do:
In our remove be thou at full ourself;
Mortality and mercy in Vienna
Live in thy tongue and heart.
However, the Duke never really gives up power. Not only is his renunciation strictly temporary, but, unknown to Angelo, he remains close at hand for the duration of the play, constantly observing and interfering. He also uses Angelo's apparent brief authority as a way of implementing harsher policies without taking the blame for them. Angelo is thus in every sense the Duke's pawn. The Duke's power is so absolute that it can never truly be renounced. The Duke can always resume his position at will, since it is his by birth, not by gift.
The social power of the Duke is amply demonstrated at the end of the play. A comedy ought to end with at least one marriage, and the Duke provides several, though they are scarcely in accord with the comic spirit. Having married off the unwilling Angelo, and the equally unwilling Lucio, the Duke tells Isabella:
I have a motion much imports your good;
Whereto if you'll a willing ear incline,
What's mine is yours and what is yours is mine.
Angelo's attempt to gain possession of Isabella is the central struggle of the play. The Duke casually arranges to marry her in the space of three lines. In this play, men do not always succeed in exerting power over women. But the Duke, by virtue of birth and station, has power over everyone.