In comparison to other world leaders who have been accused of war crimes and prosecuted for the latter like the Libyan Colonel Muammar Gaddafi, it stays up to debate why leaders like Tony Blair who supposedly committed worse war crimes have not been persecuted.
The authority to persecute individuals for war crimes lays with the International Criminal Court (ICC) that bases itself on the Rome Statute. The UK is a state party to the Rome Statute which means that the court has jurisdiction over UK nationals that commit any of the four core crimes in which war crimes are included. This means that the ICC could persecute Tony Blair based on Article 8. It is unclear why this has not taken place, given that the court has convicted other leaders accused of having committed war crimes that are deemed less problematic. It is important to note that in the case of Tony Blair, the main difficulty is to prove to what extent he himself is individually responsible for specific acts that have been carried out. It is a lot easier for the ICC to convict a military general who gave an explicit order for an operation which is deemed to be a war crime, rather than the mere instigation of the war. Furthermore, the ICC is known for a tendency to focus on non-Western perpetrators. Any court cannot try the initial breach of international law with regards to having acted without the United Security Council resolution. These facts could thus suggest that there is a lack of personal consequences for Tony Blair and a certain degree of impunity in comparison to other world leaders that have been accused of war crimes.
There is not enough evidence to individually prosecute Tony Blair for war crimes. If one assumes that Blair was led by false intelligence, we cannot assume malicious intentions (lack of mens rea) which would make a legal case against him more difficult.
All world leaders should be equally tried for the war crimes they commit.
[P1] Every crime shall be brought to justice.
Rejecting the premises
[P1] Not all crimes need to be brought to justice.