Do not seek an injunction to restrain the LibDems from behaving illegally, Lord Rennard.
What you should do is allow the LibDems to get as much rope they need to hang themselves.
What they have done is behave with manifest unfairness and trample over long-established legal principles of
- the right to be treated as innocent till proven guilty
- retrospective legislation being vindictive and arbitrary as well as going against the Rule of Law
- double jeopardy
Do not compromise, because yours is the worst case of member abuse I have ever heard, ever, if you don't count actually physically assaulting and murdering party members.
If you compromise, you will have given back party leaders carte blanche to piss and shit all over members and activists.
Your career with the LibDems is now over, but you can still make a political point by refusing to back down.