Government is an interesting question - and one of the questions "Measure for Measure" keeps asking is what constitutes good or bad government?
The Duke abdicates his office at the very beginning of the play, leaving Angelo in charge (nobody knows precisely why he does this - lots of speculation, but no absolute and total explanation given in the play). The Duke has let everything slide, he says:
We have strict statutes and most biting laws,--
The needful bits and curbs to headstrong steeds,--
Which for this fourteen years we have let slip,
Angelo is harsher, firmer - and much more merciless: how the whole plot with Claudio comes about. Is it fair for Claudio to be put to death? Is this good government - good justice? Is this how Vienna should be run?
Of course, the question of justice then directs you back to the title's question. "Measure for Measure" - what is a fair response to any given event? What balances out what? Where is the line between too lenient and too harsh?