Ask a Business Lawyer. Get Business Law Questions Answered ASAP.
If the bar is open, there is nothing which prevents them from coming inside. There is no need for them to obtain a search warrant since there is no expectation of privacy in the bar. You could tell the officers they have to leave, but once they smell what they believe to be marijuana, they then have probable cause to conduct an investigation. However, that probable cause does not extend to searching every single person in the bar.