If a foreign person enters the united states on a visa waiver (90 days) can they conduct business and if they enter into a contract with a US citizen

Although a foreign person entering the U. S. on a visa waiver for 90 days is not allowed to conduct such personal business as you describe, the immigration law restrictions would have nothing to do with the legality of a contract that you enter into with a U. S. citizen. Although there have been attempts by municipalities to make such contracts voidable, they have been declared illegal by the courts as infringing upon the federal government’s right to place restrictions upon aliens in the United States. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.