I've been trying to find some information on this and I can't seem to, so I was wondering if anyone has experimented with this more. I had a game last night where I was downed and between a teammate and an opposing character. I popped up my knockdown shield and was trying to provide them cover, but I wasn't sure if I was causing problems by creating another barrier. My guess is that you probably can't shoot through it as a teammate, but it'd be curious as a strategy.