1) The Premiership of Blair is defined not only by Iraq but the involvement of the UK in other controversial armed conflicts. Overall, he engaged the UK in five armed conflicts in a six-year period: We can count two interventions in Iraq (one in 1998 and a second time in 2003), Kosovo 1999, Sierra Leone in 2000 and the Afghanistan war of 2001. This heavy engagement can create the impression of a war-driven Prime Minister who as a result should be mainly considered for his engagement in wars.
2) Another counter argument is that the fact of having advanced national policies within the UK does not justify any breaches with International Law in the context of an armed conflict. It is possible to be a respected politician on the national level whilst being deemed a war criminal at the same time.