The Gaza-bound flotilla affair raises many questions. There are various means of investigating it; the correct method should be chosen by weighing the benefits, in terms of softening international criticism, against the risk of a biased probe. But one thing is clear: Any probe not deemed credible overseas is a waste of time.

Following is an evaluation of the main options:

b An international probe: Recent experience - both the Goldstone Committee's report on last year's war in Gaza and the International Court of Justice's advisory opinion on the separation fence - shows that international probes related to Israel are irredeemably politically biased, due to the political composition of international bodies like the UN.

b An internal Israeli probe: Military inquiries into the operation's conduct are necessary and have probably been initiated. But they are no substitute for a comprehensive probe into every aspect of the affair, including the government's decisions. No internal probe, whether military or civilian, would be seen as credible even in Israel, much less abroad.

b A government inquiry committee: This is an ad hoc panel set up to probe a given incident, whose members are appointed by the relevant minister or ministers. If the chairman is a retired judge, the cabinet can grant it the same investigative powers of a state commission of inquiry, such as the authority to subpoena witnesses and documents.

The glaring weakness of this option is that the very minister or ministers whose actions are being probed can choose the committee's members. That is why the Knesset, which passed the law authorizing such panels in 2001, intended them to be used only for "small or medium-sized matters," not issues of great public importance like a war. After the Second Lebanon War of 2006 then-prime minister Ehud Olmert chose this route, precisely because it enabled him to choose the investigators.

b A state commission of inquiry: Once the cabinet votes to appoint such a commission, its members are chosen by the Supreme Court president. It must be chaired by a senior judge, either sitting or retired. Such commissions have been used to probe other incidents that attracted international attention, like the arson attack on Al-Aqsa Mosque (1969 ) and the Sabra and Chatila massacres during the first Lebanon War (1982 ). The latter commission - which found that the government bore indirect but not direct responsibility for the killings - won international praise.

This is the best way to probe an issue of great public importance. By law, all commission hearings are public unless they deal with classified matters, so international observers could be present. In theory, the Supreme Court president could even appoint a non-Israeli jurist to the commission, though this has never been done. Commissions also have full subpoena power.

Such a commission, headed by a jurist who is widely respected abroad, such as former Supreme court president Aharon Barak, is thus the only possible answer to the world's demand for a credible inquiry.