This past Shabbos I discussed the question of what to do if you are in on etime zone and your chametz is in a different time zone. Does the issur of chametz follow the gavra or the cheftza?
This question is discussed in the Shut Oneg Yom Tov. He says that the issur follows the cheftza of chametz and therefore even if you are in a place that is not Pesach the chametz is still assur. His rayah is from the gemara that discusses what the halacha is if you eat chametz shel terumah. If you do it b'shogeg you pay keren and chomesh and b'meizid you are patur because of kim lei b'd'rabba minei. The gemara brings a rayah that you value teruma eaten based on volume eaten and not based on the value from the fact you pay for chametz teruma. If you paid based on value, teruma chametz has no value. The Oneg Yom Tov asks if the issur chametz follows the gavra then we can say the gemara is discussing a case where the teruma was eaten on 7th day of Pesach and the owner of teruma was in a location where Pesach was over. For the owner the teruma does have value. From the fact the gemara doesn't say this you see we follow the cheftza shel chametz.
The Chessed L'Avraham disagrees and says the issur of ba'al yera'eh follows the person. His rayah is from the gemara that says if you are away from home and after the 6th hour you remember you have chametz you can be m'vateil it. The gemara asks how can you be m'vateil it, it is already assur. The gemara could have answered that the chametz was in a different time zone where it wasn't Pesach. Since it didn't say this you see the issur follows the gavra.
The Mikroei Kodesh says maybe they don't argue. The Oneg Yom Tov could be talking about the issur hana'ah from chametz and the Chesed L'Avraham is talking about the issur of ba'al yera'eh. He also quotes from the Sefer HaYomom from Rav Yechiel Michel Tuchitchinsky (available for download at http://www.hebrewbooks.org/root/data/pdfs/SA/kadoorhaaretzsa.pdf (p.92) ) who addresses this question posed to him by Nathan Lamport's son in law. Rav Yechiel Michel Tuchitchinsky writes that the chametz itself is an issur cheftza and assur to eat and assur b'hana'ah. However, the issur of ba'al yera'eh is an issur gavra.
Rav Yechiel Michel Tuchitchinsky then writes an interesting idea. If someone is in EY and the chametz is in NY, you coul dbe m'vateil the chametz because it is similar to a case where you are m'vateil chametz before it is chametz. The halacha is that if you are mixing flour and water on Pesach you can say any crumbs which will be chametz are batul since it is not yet chametz. Here too the bread in NY doesn't have a "din" chamez so you can be m'vateil it. Now if you are in NY and teh chametz is in EY, we can also say that bittul works. The reason is because the only reason bittul won't work on Peasch is because the Torah puts it into your reshus against your will. In this case since it is not Pesach for you, the chametz isn't being put into your reshus and you could be m'vateil it. L'ma'aseh he says there are opinions that it is the issur hana'ah which prevents the bittul from working so l'chatchila we should be machmir. Howeevr, b'dieved the chametz is not assur after Pesach.
The Mishnas Ya'avetz wants to say that this question depends on whether chametz is an issur gavra or issur cheftza. He learns the Rambam that it is an issur gavra and therefore the issur follows the person. (However, ayin Brisker Rav that even after the 6th hour the chametz is an issur cheftza)
Rav Moshe (Cheelk 4 Siman 94) paskens that the issur follows the gavra but we should be machmir to follow the cheftza shel chometz. However in Siman 95 he seems to say it follows the cheftza. Tzarich iyun in Rav Moshe although the maskana is clearly to make sure you get rid of all chametz in a way to satisfy both time zones (whether selling or buying back the chametz)