(Obtaining an Immigrant Visa at a U.S. Consulate Abroad / Foreign Visa Appointment)
Every immigrant admitted to the United States must demonstrate to a Consular or Immigration Officer that he or she is not inadmissible on public charge grounds.
"Consular Processing" involves processing for permanent residency through the State Department. In consular processing, the interview for an immigrant visa takes place at a U.S. embassy or consulate located (with some exceptions) in the foreign person's country of nationality.
If an alien is already present in the United States, seeking to adjust his status is generally the preferred method since the Adjustment of Status applicant whose case is denied may challenge such denial through the administrative and/or judicial appellate processes. Denial of a visa a U.S. Consular post, however, is essentially a non-reviewable, non appealable order; there are limited exceptions that may permit review. In addition, Visa processing at a consular post abroad also involves the additional time and expense of traveling overseas and may further prolong the separation between family members. The Adjustment of Status applicant may reside in the United States, obtain employment authorization, and a travel document until his case is processed, reviewed, and completed by the U.S. INS.
Recent delays in I-485 processing have encouraged lots of candidates to apply for consular processing abroad, as it is faster and easier. Please review both the options very carefully before going for one or the other, as individual circumstances may vary.
There are 3 ways to do consular processing for employment based immigration. First and the simplest/fastest is to indicate while filing I-140 application that the person would do the consular processing near to his/her permanent address in his/her home country. If you specify in I-140 that you are already in US and would do adjustment of status, and later change the mind to do consular processing, you have to file form I-824 (Print 2 sided on short edge) with INS which sends the information about your I-140 approval to National Visa Center* in Portsmouth, New Hampshire. That office then makes an electronic copy of the petition and forwards it to the consular post. NVC will also create a case number and send Packet 3 (described below) to the candidate. Filing of I-824 can delay the processing considerably. The third option (which is not available to everyone, described below) is to do Attorney Certified I-140 (AC I-140) which can save lot of time.
Person who is already legally in US can remain in US until the time of interview and medical examination at a consular post. Even if the person is outside US at the time of applying, he/she can come to US if he/she has valid non-immigrant visa. Persons who go for consular processing would need to go to their home country for usually about 1 week to 10 days for the medical examination and interview.
Consular processing can be done even if you are using EAD, as long as you didn't file I-485 just for the sake of getting EAD and then promptly apply for CP. That way you abuse both the systems and invite otherwise avoidable problems.
When this page was initially written, it had most of the references for doing consular processing from Mumbai, INDIA. But most of the things written can also be applicable to other consular posts from INDIA and from other countries. Later many details from other consulates have been added and I strongly suggest that every one should read the whole document as there may be things which may be useful to you but are mentioned in another post's details.