Using a body cam when out and about

I was just wondering… with all the stories about butsukari-ya and other harassments that target foreign people in Japan… is anybody using a body cam (like the ones police use) to record everything while they are out and about?

Given that the police might tend to side with Japanese people when something happens, mightn't a discrete recording device be a good idea?

Or perhaps illegal??

Just wondering what people thought…