My husband was just in Cuidad Juarez for his immigrant interview. At the medical exam he was asked if he ever smoked marijuana. He said no, I just tried it a year ago, for fun. He went the next day for his results and they told him that they were at the Consulate. He then went to his interview and was asked one questioned and denied visa without the possibility of a waiver. My husband has worked since he entered the US illegally in 1997 and has no criminal record. Has never been a public charge. He was being honest and they punished him for 3 years. I am a US citizen and we have two kids together. I don't want to live without him for 3 years.
I am very sorry. If the denial was based on "drug abuse," this interpretation is a big problem at Ciudad Juarez and some other high traffic consulates around the world. There are ways to challenge the denial. You should contact an immigration attorney immediately.
Best of luck,
Law Offices of Patrice Dziire