I completed my leaving certificate back 1990. I received a modest 6 honours and 2 passes. None of the subjects I studied in school had any bearing on my career choice and probably did not affect my development in the Gardaí. But they enforced the idea that I didn't want a conventional job in something like business or science.
I graduated from Templemore with a Diploma in Policing Studies and a Certificate in French Studies, which is very handy when a French tourist asks for directions! Although I enjoyed my school subjects, (I had a real passion for English, poetry and Shakespeare), none of them applied to criminal law. I expect there probably are no legal subjects still, and students have to attend college to learn about the law. I couldn't wait though, and started in Templemore less than 2 years after I left school.