Blocking vision of receiver?

[yurip]

If the thrower has released the disk and the person covering you can't watch where you run and the frisbee at the same time are they allowed to just follow you and block your vision with their back to the frisbee?

If not, which rule are they infracting?

[tugbo]

Relevant rule

xiv.b.4 Vision blocking: If the marker deliberately blocks the thrower's vision, it is a vision blocking violation.

Note that only blocking the vision of the thrower is illegal. No similar rule exists for blocking the vision of the receiver.

So, not a violation.