Unfortunately you can't sue. They can always find something stupid, "he seemed disingenuous" or "we liked Ahmed for being a blank canvas with great spirit". There is a ton of arguments you can make in a case like this that would hold up in court. You have to show that they are doing it systematically in order to have any chance.

Sad reality is that large companies can discriminate against anyone. My company discriminates against men all the time. I was part of the hiring process at one point, I was one of the guys that would test applicants on technical skills, Linux, networking, db, scripting, stuff like that. I've seen great guys not being accepted in favor of women that completely failed the technical tests, were not from a tech background or have never even touched an Unix OS - this was on positions that required 7+ years . The only women that did not get an offer was one that was to scared in her interview, she thought she could not do the job, really emotional about it. Only good thing is that this girls tend to not stay for long since customers want good service and do not give a crap about the sex of the one they work with, bad thing is that they tend to fall upwards, tech companies are bending over to take women.

I've eventually asked to be removed from the process on the fact that it was hurting my mental state. Seeing the blunted discrimination is was hurting my soul.