US Islamabad Post first refused my friend’s immigrant visa under section 221(g) “your experience doesn’t meet the requirements listed on your labor certification” at the time of his interview. After one month later, consular officer sent him another objection letter via mail that was 212(a)(6)(c)(1). In which he wrote, "If you believe that this letter was sent to you by mistake. You should contact us via one of our approved courier services immediately. This will be your last opportunity to submit to evidence to us". My friend submitted evidences on April 29, 2002. He didn't get any kind of the reply from the embassy. Now, please, tell me (by law) how much time, consular officer on a review of a denial immigrant case takes? And why consular officer sent him another objection?

Consular officials are not bound by any time limit when processing cases and have great discretion in approving or denying a visa application.
If your friend believes that his application was denied erroneously, he should contact an attorney for assistance.