I am being sued by a futures broker. When hiring an attorney, what specialty should i consider?

When you say being sued by a futures broker, do you mean that an NASD arbitration has been commenced against you?  If so, it sounds like you should look for a litigator who has experience in NASD arbitrations; if not, just a litigator with experience in securities law cases.  As to whether you can countersue the broker, do you have any basis to claim that the broker owes you money?  If so, you can countersue (although you may, depending on the nature of the claim and the provisions of your contract with the broker, have to assert your claim or claims in a separate proceeding); if not, but you simply contend that you don't owe the broker money, tha tis not a counterclaim, but merely a defense.