(URGENT!!) Can a high-school conduct a drug test without parental consent?

BACKSTORY:

My brother recently got his ears pierced during the term 1 holiday and as anyone would know, you are not allowed to take the piercing out for a few weeks or it could infect/close the whole. He and my parents were fully aware that a boy wearing piercing to school is against the code of conduct however in the schools policy, the most they can do about it is a detention which my brother was more than willing to sit.

Today was the first day of term 2. My brother was not feeling well this morning but he still went to school. He had messaged my parents around 10am asking to go and fetch him but due to work, they couldn't so they told him to just lay down and take a nap if he needed to and they would deal with the school. (The school does not have a designated area where students can go if they are not well, such as a sickbay or anything like that. They make the sick kids sit in the library for over an hour before they even attempt to call the parents)

My parents got a call from the school at 2.30 (closing time) from the vice principal and he told them that they are going to keep my brother at the school for a drug test and search. My parents did not consent to this and they did not give the school permission to do so. They are now saying that they are going to keep my brother at the school until my parents go there to consent for the drug test and search.

Are they allowed to do this? Their reasoning for a drug test and search is due to the piercing which makes no sense.

please help!!! URGENT!!!