Some good news: look at
this article, in particular this section:
"
2. Criminal and Related Grounds:
Excludable on criminal and related grounds are the following:
1. Aliens convicted of, and those who admit having committed either
1. A crime involving moral turpitude (or an attempt or conspiracy to commit such a crime), or
2. A violation of (or a conspiracy or attempt to violate) any law or regulation relating to a controlled substance.
Exceptions: an alien will not be ineligible for a visa if the alien committed only one crime involving moral turpitude and if
1. the crime was committed when the alien was under the age of 18 and the crime was committed (and the alien was released from any confinement imposed for the crime) more than 5 years before the date of application for a visa or admission to the U.S., or
2. the maximum penalty possible for the crime did not exceed imprisonment for 1 year, and if the alien was convicted of such crime, the alien was not sentenced to a term of imprisonment in excess of 6 months."
If your crime was simple assault (i.e. without actual bodily harm) then you should be covered by the second exception. Even if not, the article says it is possible to get a waiver for immigrant visas if
"
the activities for which the alien is inadmissible occurred more than 15 years before the date of the application for a visa, admission to the US or adjustment of status, and the alien’s admission would not be contrary to the national welfare, safety, or security of the US, and the alien has been rehabilitated."
which should cover your case. As I said, the best thing for you would probably be to contact an immigration attorney. You may want to look at
these guys. I don't know anything about them, I just found about them on Google, but they are based in London and seem to specialise in US law. The article I quoted was taken from their site. They should also be able to advise you on the possible consequences (if any) of your having used the VWP to visit the US. Good luck!
