The landlord went all the way to the state supreme Court and won, the court agreed that it was unlawful to search the landlord's property without his consent, even though he didn't live there.

Now you have an unlawful foreclosure. 

I handled the legal proceedings myself (sort of) so it didn't cost me anything except my time.In my situation the PO knew that the house was going to foreclosure auction and tried to bring federal legal action against the bank (mortgage co) citing unlawful foreclosure in order to stop or reverse it. 

Is it possible to represent and file the unlawful detainer yourself? 

Texas in many cases awards triple damages to tenants being unlawfully treated by landlords.

This process is referred to as an unlawful detainer and can usually be completed within four to six weeks.During this process it isn’t uncommon for the lender to send out a “Boarding†crew to go out to the property and change the locks and board up the windows in fear of vandalism.

Interpretation of this agreement to arbitrate shall be governed by the Federal Arbitration Act.(2) EXCLUSIONS FROM MEDIATION AND ARBITRATION: The following matters are excluded from mediation and arbitration: (i) a judicial or non-judicial foreclosure or other action or proceeding to enforce a deed of trust, mortgage or installment land sale contract as defined in California Civil Code §2985; (ii) an unlawful detainer action; (iii) the filing or enforcement of a mechanic’s lien; and (iv) any matter that is within the jurisdiction of a probate, small claims or bankruptcy court.

If the tenant will engage in a discussion, there is a much better chance of the move-out going as good as could be expected.... mitigation of damages too.In twenty years, with 15 units, we have only had three evictions that went to court for unlawful detainer.

Or, it's conceivable, that previous owner was in R-1 and petitioned for an "exception".....in which case you'd also be grandfathered as a lawful duplex.c) unlawful conversion of a single family home into an illegal duplex.

The paperwork shouldn't be too difficult and the process goes like this in Virginia:1) Post a 5-day pay or quit notice on the door (can find examples of what this should look like online)2) After 5 days, if they have not moved out or paid, go to general district court and fill out the eviction form (Unlawful Detainer), pay the fee, and get a court date3) Show up to court and explain what had happened4) If the judge is nice he will give you immediate possession5) Possession is not immediately yours until the sheriff shows up!