There have been tens of International inquiries into events in the Gaza Operation, and Israel has cooperated fully with almost all of them. Only in those instances where it seemed clear beyond any doubt that the initiative was motivated by a political agenda and not concern for human rights, did Israel decide not to cooperate. Unfortunately the Human Rights Council Fact Finding Mission (the "Goldstone Mission") was one of these.

Why does Israel claim that the Goldstone Mission was politically motivated?

Three reasons:

§ The Resolution establishing the Mission prejudges the outcome of any inquiry. Prior to any investigation, it determines that Israel has "caused massive violations of human rights" and accuses Israel of targeting medical facilities and systematically destroying Palestinian cultural heritage. It does not accuse the Hamas of any violations. The one-sided nature of the resolution was the reason it was not supported by many States, including Canada, Japan, Switzerland the European Union.

§ The Mandate of the Mission is similarly one-sided. It calls for an investigation into violations of international law by "the occupying Power, Israel, against the Palestinian people."  It does not mandate any investigation of violations by Palestinian terrorist organizations. It was for this reason that many distinguished individuals who were asked to head the Mission refused.  One of them was Mary Robinson, former High Commissioner for Human Rights, who described the mandate as: "not balanced because it focuses on what Israel did, without calling for an investigation on the launch of the rockets by Hamas."

§ Members of the Mission: At least one of the Mission's members has a clear bias on the issues under investigation. During the very conflict which she is now supposed to be impartially investigating, Professor Christine Chinkin was signatory to a letter to the London Sunday Times, asserting that Israel's actions "amount to aggression, not self-defense" and that "the manner and scale of its operations in Gaza amount to an act of aggression and is contrary to international law".
 

Wasn't the mandate of the Mission changed to be more balanced?

Justice Goldstone has claimed that the Mandate of the Mission was changed, unilaterally, by the then-President of the Council. However, as a matter of law, the only body with the legal authority to modify the Mandate is the Council itself, and it has never done so.

Additionally,  it should be noted that even the so-called changed mandate focused on events in Gaza, between the dates December 27, 2008 and January 1, 2009, effectively ruling out any attention to the years in which thousands of missiles were fired on civilians  Israel prior to the start of the military operation.

Finally, even if were the Mission to operate according to new and different terms of reference of its own devising, all subsequent proceedings by the Council following its report would still be based on the Council's own biased Resolution and Mandate.

Wasn't the Mission balanced in practice? Didn’t it invite all sides to present evidence at public hearings?

Israel was concerned by reports in the Palestinian media that at every stage of their visit to Gaza the Mission members were accompanied by Hamas representatives. If so, this was clearly a major obstacle to obtaining genuine evidence, particularly regarding Hamas' violations of international law, and its use of civilians as human shields.

The unprecedented decision of a fact-finding mission to hold public hearings was also troubling. The very point of a fact-finding mission is that a team of experts bring their experience and judgment to bear in assessing the available evidence and drawing responsible conclusions - not that emotional allegations are directly broadcast into the public arena, without any possibility of taking confidential or sensitive information into consideration.

Can't Israel rely on the neutrality of the UN Human Rights Council?

Unfortunately not. The Human Rights Council has consistently singled out Israel, while failing to address the true violators of human rights. It has devoted more resolutions to condemning Israel, than to all the other countries of the world combined. Needless to say no resolution or fact-finding mission was initiated by the Council concerning the firing of 12,000 rockets and missiles on Israeli civilians during the years prior to the Gaza operation.
 
Justice Goldstone himself admitted, in an interview to Al Jazeera "I can understand Israel's suspicion with regard to the Human Rights Council - it has been partial with regard to Israel for many years".

But if Israel doesn't cooperate, won't wrongdoers go unpunished?
 
Israel is committed to ensuring that its forces act in accordance with international law, and the rules of armed conflict form part of the training of every soldier. In case of any allegations that these principles have not been upheld, Israel is committed to fully investigating and prosecuting offenders. Additionally, any decision not to investigate or prosecute an alleged offence can be appealed to Israel's Supreme Court.  

Following the conclusion of the military operation in Gaza, Israel initiated a series of far reaching command investigations into various aspects of the conflict, as well as many dozens of specific investigations into particular allegations of improper conduct by soldiers. In the past, such investigations have led to criminal prosecutions and convictions, and in this case a number of criminal prosecutions regarding wrongdoings are already in process.