ugh, I know this all to well. My favourite to-date was being blasted by a direct ally (as in, someone within my own lawful faction) for attacking a pair of nomad and outcast caps in a fighter. I mean there was never any risk of me winning against both, but this ally sided with their own enemy against myself and got other lawful allys to jump in because they were familiars to eachother. All the while myself following vanilla RP (and actually RPing it), whilst this ally was proclaiming they were a "special operative". In actuality, they really had the same ID and rights as me (whilst even having an inferior IFF).
To be honest, when faced with cliques like that, there isn't much you can do. That is, without //metagaming or reporting the pvp abuse, which sucks nads. Reporting people isn't fun for anyone and I'm sure most would rather avoid it.