Yellow Sash of Power

Perhaps it's because schools on TV are constantly forced to deal with teacher shortages. Perhaps it's just an excuse for writers to use all of those police tropes. For whatever reason, one position of responsibility seems to crop up time and time again in school-based shows... the position of hall monitor. These kid cops are given as much powers as teachers... they're allowed to stop their fellow classmates, interrogate them, demand hall passes, and in some extreme cases, even allowed to assign detentions. They've been given the Yellow Sash of Power.

The trope can take several forms. Sometimes, a character who is aware of all the power the position carries desperately wants to be hall monitor, in other cases, a character who worried about all the power going to his head will be very reluctant to put on the sash. Usually, the latter are the ones who receive the sash, and they're always the ones who let it all go to their head.

Normally this trope is used to teach a lesson about how someone must be careful not to abuse authority that is given to them.

Compare Absurdly Powerful Student Council, another example of students having way more authority than they would in real life. See Also: Red Armband of Leadership

Examples of Yellow Sash of Power include:

Literature

Lampshaded in Harry Potter and the Order of the Phoenix, where a couple characters specifically point out how outrageous it is to give students the level of power the Inquisitional Squad has been arbitrarily granted.
- Not that it stops them.
In the first part of Brightly Burning, Lavan is sent to a school where the headmaster had decided to cut costs by devolving all disciplinary authority to the Sixth Form students. These students repay this trust by bullying the younger students, forcing them to provide treats or entertainment for them and do their homework for them, and caning anyone who objected or disobeyed. When the leader decides to give Lavan eighty lashes for avoiding him and not stealing a tunic length of highly expensive red velvet for him, Lavan's latent pyrokinetic abilities trigger and burn several of the Sixth Form students to death. The investigation afterwords reveals the excesses of the Sixth Form and gets the school shut down until it can be reorganized.

Live Action TV

On an episode of The Brady Bunch, "Law and Disorder," Bobby is made Safety Monitor and proceeds to abuse this power at school and at home.
Even Stevens dialed this Up to Eleven. Incorrigible Louis is sentenced to hall-monitor duty, which involves an absurdly over-the-top induction ritual, the power to issue detentions and even dispense retributory wedgies to hallway bullies, and ultimately an investigation of administrative corruption.
In an "On Deck" episode of The Suite Life of Zack and Cody this trope is played completly straight; Zack is made Hall Monitor in an effort to teach him responsibility. He ends up being far too zealous, even using a speed gun to trap walkers going too fast. He makes himself very unpopular throughout the ship. An Aesop is delivered in a very Anvilicious manner.

Western Animation

In Hey Arnold!, Phoebe is made hall monitor despite her intense reluctance. At first, she is an absolute pushover, but after a pep talk from her friend Helga, Phoebe does a complete U-turn, even pulling people away from the water fountain if they're taking too long.
In The Simpsons, Bart surprised his principal by being a fairly credible hall monitor, though he did admit that the main draw was the sense of power and being exactly the kind of person who knows how troublemakers act.
The Adventures of Jimmy Neutron: Boy Genius features another example. Master Neutron is granted hall monitor powers, and inspired by his idol Albert Einstein (who he also believes was once a hall monitor), takes full advantage of his new position, placing people in detention for possession of gum and, in Carl's case, having more llama stickers on his lunchbox than the permitted amount.
SpongeBob SquarePants takes this trope to its "hilarious" extreme. After SpongeBob is made hall monitor, he believes his jurisdiction to be the entire town of Bikini Bottom, and eventually ends up searching for a criminal known as the Maniac... without realizing that the only maniac running around is him.
On Family Guy, Peter Griffin becomes president of the school board, and ends up hiring a Humongous Mecha to police the halls, in a clear Shout-Out to ED-209 from Robocop. During the closing credits, the mechanical "hall monster" even malfunctions and ends up blowing away a teacher.
Averted in Fillmore!, which treats the sash as the equivalent of a policeman's shield, with limits on authority and an abundance of accountability.
Parodied on South Park in "Miss Teacher Bangs a Boy", where Cartman is given mandatory hall monitor duty and turns himself into a pastiche of Dog the Bounty Hunter ("Dawg the Hall Monitor"), going after anyone (even teachers) who doesn't have a hall pass and generally looking for any excuse to use his bear mace.
In The Buzz on Maggie episode "Pieface", the hall monitors are shown as having a huge amount of power and resources; including a helicopter.
Hall Monitor Sasquatch from My Gym Partners a Monkey.