COLLive is reporting that the Israeli Chief Rabbi Rav Dovid Lau was asked by the Rabbis of the Rabbinical Center of Europe to sell the chametz of all of the Jews of the Diaspora, even of the Jews who are not aware of it. Rabbi Lau agreed to do so and said he will put a clause in the contract of sale used by the Chief Rabbinate stating that the sale will apply to the chametz of all Jews.

This is interesting.

To put aside the more "minor" issues:

1. obviously the sale would need to take into account the dates - you don't want to buy back chametz for Jews in America while it is still Pesach for them, making them liable as owners of chametz on Pesach, nor would you want to sell the chametz of Australian Jews only after Pesach has begun for them already. So the sale dates need to be worked out if this is going to be done. Not a big deal, but something to take into account.

2. why ask the Israeli Chief Rabbi to do the sale - why not do it themselves? They are rabbis and perfectly qualified.

3. Why did they ask on behalf of all Jews of the Diaspora rather than just the Jews of Europe, the Jews under their domain? Is there no issue of jurisdiction of sorts? can a rabbi anywhere do something on behalf of Jews anywhere, without either side knowing each other or even knowing of each other's existence?

The bigger issue, I think, is the Chief Rabbi, or any Rabbi, selling chametz for other people without them knowing about it. I have heard shiurim on this topic in previous years and there are varying opinions as to whether or not this is a good idea, and even if it works or not. 

The main, or only, reason to allow it is to "save" the Jews from sinning unwittingly. This would be using the concept of zachin l'adam shelo bfanav" - זכין לאדם שלא בפניו - we can help bring merit to someone without their knowledge or explicit acquiescence. Jews can be assumed to not want to sin, and a Jew keeping his chametz would, could, only be out of ignorance. I can sell someone else's chametz because had he known he is supposed to he would really want to, and I am bringing him merit by doing so, as I am preventing him from sinning.

On the other hand, the arguments against allowing this include issues such as theft. By selling his chametz, if he should eat it on Pesach or sell it to a customer, he is basically stealing, unwittingly, from the non-Jew who bought it before Pesach. You might have saved him from violating the prohibition of chametz (though definitely not if he eats it), but you turned him into a thief. 

Other, maybe more minor, issues include whether you have the ability to sell someone's possessions without their knowledge or not, causing a possible double sale, and others.

I guess the Chief Rabbi feels it is ok, and maybe even a good idea. Again, I don't know why this group of European rabbis needed to involve the Chief Rabbi of Israel rather than doing it themselves, but ok. It seems kind of bold, to act on behalf of millions of Jews around the world who don't know or care or are interested or anything, but if anyone is in the position to be so bold, I guess it could be the Chief Rabbi of Israel.