School employees searching student lockers can be a big concern. However, as students enter onto a school campus it becomes the responsibility of the school to keep the students safe. Schools operate under a "reasonable suspicion" that they can search through a students personal belongings. If a employee of the school is designated and trained to perform the searches, the the concerns will be much less.
The school should create rules and guidelines for teachers that go through the proper procedure of going through lockers and when lockers can be checked. Students should also recognize that the minute they put something in the locker it is no longer private. If it is not on them or in their back pack then they can not keep it from getting in to the teachers hands.
You feel powerless. You are powerless. They already require those students to go to school and then they abuse that fact. Since they can't just be like "ok then we won't go to school" they can do pretty much anything to them. We should be more considerate not less since they are required to be there. High school students should be allowed to unionize and the union calling a strike with an appropriate grievance should be considered an exception to compulsory education laws.
Teachers, have the right to search school lockers, on school grounds, that power exists for a reason, school lockers are meant to store your books school gear that you can not take home with you every night.
If students are hiding things in there lockers, they should not have (Drugs, firearms/weapons, stolen property and other contraband) they need to be caught. Most of you are lucky you get doors on your lockers during school, at the school, I went to the lockers were designed with no doors so any one walking past could see what you have.