Robin:

We use two firms for U.S. derivatives advice - both in New York and both 
highly recommended:

David Mitchell of Cadwalader, Wickersham & Taft (212)504-6285
Ken Raisler of Sullivan & Cromwell (212)558-4675

David we use for contract issues - what should our forms look like under 
various conditions, etc. and Ken, who is a former General Counsel of the 
CFTC, we use for policy questions, political (lobbying) and e-commerce 
issues.  Please feel free to use my name when contacting either of them.  If 
neither of these is exactly what you are looking for, let me know and I can 
put you in touch with others.

Mark