A high school is conducting a mandatory full-body (including rectal cavity and genital area) search of every student due to the high use of vape devices in said school. is this legal

No.

Explanation:

The high school will have to obtain permission from the each individual student for the full-body search. If no permission is given, then they cannot conduct the search.

See the Tinkers vs. Des Moines case, which states that, quote, "Students do not shed their constitutional rights at the school house gates". This constitutional right includes the right to privacy, which is protected under the 4th Amendment, which states, quote:

The right of people to be secure... against unreasonable searches (which is a full body-search,)... shall not be violated... [Fourth Amendment].

A student may volunteer for such a search, but the school cannot force all students to go through the search without it impeding their rights.

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answer:

the colonists had their reasons for creating a weak central (federal) government under the articles of confederation. not only did they create a weak federal government, they restricted the powers of the state governors because they were so concerned about the leaders abusing their power.