Before police officers may raid an entertainment venue, they must first obtain a search warrant from a magistrate. The warrant gives police the powers to search every person in the venue when it is raided, and to demand urine samples from customers.
Police believe that innocent people have nothing to fear and will prove their innocence by providing a urine sample.
You have the right to refuse to give a urine sample, but your refusal will be tantamount to obstructing an officer in carrying out the law.
Officers - acting on the suspicion that you have taken drugs - then have the right to place you under arrest until you do provide a urine sample.