I'd like you to cite the part of the law where you think the Selective Service violates the Civil Rights Act. Keep in mind that not forcing women to serve in the military is not barring them from doing so. Also, I might add, even if the laws regarding only drafting men contradicted the civil rights act, the civil rights act is not a constitutional amendment so it would not trump the law congress passed saying that only men had to register for the draft.
Also, you may want to read this:
http://usmilitary.about.com/od/joiningthemilitary/a/enlstandarRAB.htm
Or better yet, take a look at this supreme court ruling upholding that the law congress passed to only draft men was Constitutional as women were barred from corabat roles and the draft would be used to fill corabat roles. So it was in the state's interest to discriminate who they would draft/not draft based on sex. So... Yeah. Like I said, the government can discriminate if it has a state interest to do so. (And you can look at Supreme Court rulings to that affect as well, if you like).
http://www.law.cornell.edu/supct/html/historics/USSC_CR_0453_0057_ZS.html
CliRAB: That law isn't "unlawful". And the Supreme Court has even ruled to that effect and that it followed the Constitution.