There has been a lot of police rainwear over the years. The traditional wool blend cape. The black Gannex Mac and a long foam filled nylon coat. The long nylon mac gave way to a short coat and nylon leggings. Having said all of that it's a rare sight to see an officer walking these days.
I still have one of those very heavy navy blue nylon police raincoats, a relic of a time when a late (male) partner collected police gear of all types. The label inside says "A genuine ScottyMac" and it has the shoulder loops to attach the epaulettes that would have been worn by a policeman on duty. Your posting has reminded me I must get it out and wear it next time there is a really heavy downpour.