Can somebody arrested, charged and bailed for Heroin/Cocaine trafficking, but is acquitted because of a "technicality" then be allowed into the US?

Hello,  It depends. It is not clear whether you were acquitted in the U.S. or the U.K. If the criminal trial took place in the U.S.  then there is a strong likelihood that at the U.S. border, the Immigration Agents may deny you entry if they deem you to be a drug trafficker even though you were not convicted of drug trafficking. It may be a good idea to apply for a visa at the U.S. consulate in your country of residence before incurring the cost of a ticket. This would give you an idea of the possible problems you may encounter as you try to visit the U.S.   Disclaimer: This information is of a general nature and is not, nor is it intended to be, legal advice. You should consult an attorney for advice regarding your individual situation.