How to approach teacher about my brother's non-uniform coat being seized?

Solution is clear. Student should apologize and parent/guardian should collect garment. As has been outlined to you.

Or else you could go on a big crusade about how terrible the school is etc etc... if I were a betting man...

CALL THE GUARDS?????REALLY???

While maybe not being legal, calling the guards will make a mountain out of it and the teachers could have it in for him then.

As others have mentioned, talk logically re safety and how he's now more endangered when cycling to school (in an environmental friendly way)

Uniforms have their place in school. A crested top and trousers or skirt.

Mandatory jackets, blazers, coats, gabardines, parkas etc on top of that are as dumb as soup. Pure vanity and snobbery.

Surely he should have the school uniform for Wearing in school and whatever else is weather and safety protection for wearing while cycling to school.

So it depends on the detail of having it in school, ie. did he also have the school jacket?

Utterly insane. I'm so glad I didn't go to primary or secondary school here, though I did attend college in Ireland. Even in 3rd level you could see this pervasive notion of the lecturers being some God like being never to be questioned, who could treat students like dirt, while everyone was afraid to speak up about it.

Where I grew up we didn't have uniforms and for a lot of kids their clothes were very important. And if you met some of those kids' parents... Let's just say a teacher would know to never ever in a million years take a coat off any child, as they would have a very slim chance of not ending up in the hospital or worse.

I remember one student had a hat he wouldn't take off which wasn't allowed and a teacher confiscated it. Now, at the time I thought the teacher was somewhat in the right (none of us were allowed to wear one even though baseball hats were very popular). There was no good reason to wear one unlike this case with safety for cycling.

Turned out it was a hat that belonged to the kid's brother who had died (still not really a good reason but that doesn't matter). And this kid, like many of my classmates, had a lot of cousins. As it was a woman teacher who took the hat it was the boy's girl cousins who showed up at the school, and by the time they were done with her she was missing chunks of hair, face scratched to hell, blood everywhere, clothes torn. And she didn't come back to teach for the rest of the year.

Someone suggested going in guns blazing would end up with the boy being treated badly by other teachers. Well, do you think any of the teachers treated this kid badly the rest of the year? (Not that I condone what happened.) Like hell they did. He wore that hat until he graduated.

It's not actually theft. No more than a teacher confiscating a mobile phone being used during class. Or an employee having to follow certain rules at work. So it's over the top to report it to the Gardai and they'd laugh at that and tell you to cop on.

Still, in the Op's case, I'd be going in and giving the teacher and principal hell about this and demand an explanation about why it wasn't handed over for the journey home, seeing as it's a reflective safety jacket for cycling.