Can you be deported if you are not in the U.S.?

It would seem illogical that you could be "deported" from the U.S. when you are not physically present in the country.  However, this can happen in a rare situation if you have a non-immigrant visa or a conditional green card and leave the country without notifying U.S.C.I.S. of your change of address.

It is possible that after you left, U.S.C.I.S. issued a Notice to Appear before an immigration judge  to your last registered U.S. address to determine your status in the U.S.  Under INA § 212(a)(6)(B), "Any alien who without reasonable cause fails or refuses to attend or remain in attendance at a proceeding to determine the alien's inadmissibility or deportability and who seeks admission to the United States within 5 years of such alien's subsequent departure or removal is inadmissible."

Additionally, if you fail to appear for your Hearing, the Immigration Judge can go a step further and order you removed.  Under INA § 212(a)(9)(A)(iii), "Any alien who has been ordered removed under any other provision of law or departed the United States while an order of removal was outstanding, and who seeks admission within 10 years of the date of such alien's departure."

It is important to note that all of this can happen even though you are not in the U.S.  From the U.S. government’s perspective, the offense is failing to appear for a scheduled hearing.  If you fail to change your address before you leave the U.S. and are subsequently issued a Notice to Appear to that address, you could be ordered removed despite the fact that you never actually received the notice and are not physically present in the U.S. at the time of the hearing.

If you have been ordered removed and are hoping to return to the U.S., you will likely need to file form I-212: Application for Permission to Reapply for Admission into the United States After Deportation or Removal.  As always, it is prudent to consult with an attorney before filing any documents to see if you have any other legal remedies.