doom > judgement, sentence
3 What justice ever other judgement taught,
justice > [system of justice]
4 But he should die, who merits not to live?
But > [But that]
5 None else to death this man despairing drive,
drive > drives; drove
6 But his own guilty mind, deserving death. 7 Is then unjust to each his due to give,
Is > [Is it]
8 Or let him die, that loathes living breath, 9 Or let him die at ease, that lives here uneath?