Can the FCC revoke an amateur license for unwelcomed use of another amateur's private/closed repeater system?
It's clear that private repeaters are allowed, per 47 CFR 97.205(e):
Limiting the use of a repeater to only certain user stations is permissible.
Someone summarized this here https://ham.stackexchange.com/a/236/1362 as saying that an owner "can legally prevent someone from using their repeater", that is, under FCC jurisdiction a ham repeater doesn't have to be available to all hams. A club may limit usage to only its members, an individual may limit usage to only certain friends/family, a linked system may limit access to those who are deemed worthy, etc.
So a repeater operator may take measures to limit use of their repeater. Seems they could:
- set up a CTCSS code and try to keep it secret
- leverage some digital protocol with a real authentication scheme
- deploy a sophisticated multi-receiver TDOA triangulation setup able to isolate and thereby retransmit only signals appearing to emanate from certain pre-approved locations
- simply shut down their repeater whenever there's unwanted traffic
All those means of "limiting the use" would be "permissible". But what if they don't work? Or what if the control operator of the repeater doesn't implement any actual physical/technical limitation but simply makes up some rules "limiting" who they want using their repeater?
In what way (and by whom) would such a limit be enforced?
I can't find any rule in Part 97 that says anything like "your signals may not be retransmitted by a repeater station unless you have permission from its control operator" or "when a frequency is reserved for the exclusive use of another station, the intentional transmission of CTCSS tones is prohibited on that frequency" or anything.
Say I were to set up a completely open (technically) repeater, but say "I hereby limit the use of this repeater to Eve and Mallory only". If Alice and Bob make a habit of using my repeater anyway (giving priority to emergency traffic, not interfering or profane, simply exchanging messages between licensees…), have they broken any specific FCC rule? Does breaking my personal rules "limiting the use of a repeater to only certain user stations" give the FCC grounds to prosecute Alice/Bob for transmitting an otherwise-authorized signal that gets picked up by the repeater I operate?