What gives the right to public schools to confiscate your phone?

Question

I've seen a few questions like this one on this site, however, I have not been able to find a credible source dictating what gives schools the power to confiscate a device?

Let me give an example:

Bob goes to a public school in the United States. Bob's school has a policy that allows the school to confiscate Bob's phone if he does not use for "educational purposes" or misuses it during class. At the beginning of the year, the school sends out a document where Bob and his parent/guardian are supposed to place their initials which means they agree to the handbook. Bob and his parent/guardian return the document, however, do not sign/agree to the handbook. What gives the school the right to legally confiscate Bobs phone without his consent? (Please be specific)

Answer 1

A teacher of children and more general the school is in loco parentis while the children are at school, which means that the school has the authority of a parent over a children in the parent's absence.

This authority arises under state common law, rather than federal law, so the relevant legal authority would differ from state to state, but would be present in almost every state.

For example, an analysis of this concept in the context of random drug testing of students engaged in extracurricular activities where the school's common law authority is balanced against constitutional concerns about privacy under the 4th Amendment is found in the U.S. Supreme Court case Vernonia School District 47J v. Acton, 515 U.S. 646 (1995).

Answer 2

Right as a controller of property

They own the property - they can set rules that must be followed while a person is on their property. If you do not follow the rules you are trespassing and must leave when requested. If you do not leave you are subject to arrest.

Right as a school

More specifically, each jurisdiction has laws regarding education and the rights and obligations of the school and the student. In every one of them, the law will permit the school to establish reasonable rules that the students must follow in order that the school can perform its function.

In this case the school has set rules around phones. They appear to be reasonable. They have advised the student and their guardian of the rules. They would be legally enforceable.

The relationship between a school and a student is not contractural (even private schools - the contract is not with the student). It is not necessary that the school get the student's agreement to the rules. The rules are enforceable without agreement.