Why does a highschooler (in the US) who has turned 18 still need to have liability waivers signed by parents?

Question

This is assuming that the waiver pertains to a school activity like a field trip.

Answer 1

There is no legal need for this to be done (and arguably, a waiver signed by a parent and not by an eighteen year old student in addition or instead, is not even a legally valid waiver).

But the "permission slip" system for K-12 schools (which is generally devised at the school district level) has almost no students in grades K-11 who are eighteen or older, and the median age at which students start their senior year in high school is 17. For seniors in high school, probably less than 3% of seniors are eighteen years of age or older at the start of the school year, and less than 6% are eighteen years of age or older at the end of the school year. Bureaucratic inertia and long settled institutional habits can often overwhelm what is legally necessary.

I suspect that in most cases, the forms are written for a parent or guardian of a student under eighteen (or at least implicitly assume that the student is under eighteen) and that an eighteen year old student who insisted could sign on their own behalf if they made enough of a fuss over the matter in most school systems that present a form for a parent or guardian to sign.

The other factor is historical inertia.

Students were not considered to be legally adults until age 21 for most legal purposes until shortly before the voting age in the U.S. was reduced from age 21 to age 18. This happened for federal elections in 1970 (first through federal legislation and then later that year through the 26th Amendment to the U.S. Constitution) in response to the fact that men under the age of twenty-one were being drafted for the Vietnam War and it felt unfair to deny men who could be forced to serve in the military for their country the right to vote. Some U.S. states started to shift the age of majority from 21 years to 18 years in the late 1960s, before this change took effect for purposes of federal elections.

Prior to that, colleges and universities were in loco parentis for students under the age of twenty-one, which basically made higher educational institutions legal guardians of most of their students, and needed to be given that authority from a parent or guardian of the college student (unless the college student was emancipated).

A fifty-five year lag from a change in the age of majority to a change in school district policies and procedures and forms is slow, but again, bureaucratic inertia is a powerful thing. Institutional habits are often not questioned in any meaningful way, even long after they become obsolete.

Finally, there isn't a lot of feedback and pressure to fit the bureaucratic requirements to the state of the law.

Every student's parents or guardians probably have to sign several general permission slips at registration time at the start of each new school year (when even seniors in high school are least likely to be eighteen years old yet), and several more over the course of the year for particular events like field trips. Over the course of a student's K-12 education, a student's parents or guardians will typically sign about a hundred of them. And, in a typical school system there may be several hundred, if not thousands of students in each grade cohort.

But in a typical school system, those waivers and permission slips will actually be invoked in connection with a legal dispute, maybe once every five or ten years, at most, and as noted before, perhaps 95% of the time, the student whose waivers or permission slips are at issue in that legal dispute will have been under the age of eighteen at the time relevant to the legal dispute. The vast majority of the time it is empty red tape with no practical legal effect.

So, the issue of a legal dispute for which a waiver or permission slip is relevant involving a student aged eighteen or older has probably only come up ever in only about 25%-50% of school districts since eighteen years of age became the age of majority, and only once even in the lion's share of those school districts. And, even in those cases where it did come up in a case involving an eighteen-year-old, the downside to having a parent or guardian sign rather than the eighteen-year-old signing personally was probably minimal, from the perspective of the school district. In most cases, the student's voluntary participation in the activity was probably held to have ratified a parent or guardian signature. Often, any waiver would also be reinforced by governmental immunity from liability. And, in those where it didn't and the school had some legal liability as a result, the cost would usually be paid for by a liability insurance policy or a collective local government insurance pool.