While others might want to comment further, I'll simply point out that 'common assault' does NOT constitute 'moral turpitude'.
Assault only becomes 'moral turpitude' if it's
(a) with intent to kill ; or
(b) with intent to commit rape ; or
(c) with intent to commit robbery ; or
(d) with intent to commit serious bodily harm; ; or
(e) with a dangerous or deadly weapon
If your American attorney says otherwise, direct him to Page 6 of Volume 9 of the Foreign Affairs Manual issued by the U.S. Department of State :
http://www.state.gov/...rganization/86942.pdf
Chris