(1) Except as provided in section 79-265.01, each school district shall adopt a policy requiring the expulsion from school for a period of not less than one year of any student who is determined to have knowingly and intentionally possessed, used, or transmitted a firearm on school grounds, in a vehicle owned, leased, or contracted by a school being used for a school purpose or in a vehicle being driven for a school purpose by a school employee or his or her designee, or at a school-sponsored activity or athletic event. For purposes of this section, firearm means a firearm as defined in 18 U.S.C. 921. The policy shall authorize the superintendent or the school board or board of education to modify the expulsion requirement on an individual basis.

Except as provided in section 79-265.01, the following student conduct shall constitute grounds for long-term suspension, expulsion, or mandatory reassignment, subject to the procedural provisions of the Student Discipline Act, when such activity occurs on school grounds, in a vehicle owned, leased, or contracted by a school being used for a school purpose or in a vehicle being driven for a school purpose by a school employee or by his or her designee, or at a school-sponsored activity or athletic event:

(3) The expulsion of a student for (a) the knowing and intentional use of force in causing or attempting to cause personal injury to a school employee, school volunteer, or student except as provided in subdivision (3) of section 79-267 or (b) the knowing and intentional possession, use, or transmission of a dangerous weapon, other than a firearm, shall be for a period not to exceed the remainder of the school year in which it took effect if the misconduct occurs during the first semester. If the expulsion takes place during the second semester, the expulsion shall remain in effect for summer school and may remain in effect for the first semester of the following school year. Such action may be modified or terminated by the school district at any time during the expulsion period.

(4) The expulsion of a student for the knowing and intentional possession, use, or transmission of a firearm, which for purposes of this section means a firearm as defined in 18 U.S.C. 921 as of January 1, 1995, shall be for a period as provided by the school district policy adopted pursuant to section 79-263. This subsection shall not apply to (a) the issuance of firearms to or possession of firearms by members of the Reserve Officers Training Corps when training or (b) firearms which may lawfully be possessed by the person receiving instruction under the immediate supervision of an adult instructor who may lawfully possess firearms.