The Co-operative Apartment:

As you know, what you really own is stock and you have a Proprietary Lease. Therefore, if you don't pay the maintenance or additional maintenance or if they accuse you of somehow making trouble, you can find yourself in Housing Court. These cases can be brought either as Non-Payments or Holdovers. There are some similarities to rental cases and some important differences. Some of these are legal distinctions pertaining to things like who is responsible for repairs inside the apartment. Some of these differences arise from the nature of co-ops. If you have a large amount of equity in your co-op then that may increase the temptation for the co-op to try to hold you responsible for their legal fees. These legal fees can become quite large. Some co-op disputes become much more bitter than rental disputes.

How an Attorney Can Help:

An attorney can help by analyzing the case and helping the apartment owner determine a strategy of how to proceed. An early settlement could be very beneficial, as long as there are no traps hidden in the language of the stipulation with the potential to open up greater liability in the future. If litigation is decided upon then it is imperative that you fight to win. You do not want to lose and get stuck with their legal fees. Co-ops are typically much more aggressive about pursuing legal fees than rental landlords.
Co-op owners may also want to visit ForeclosureFights.com, as there is information there pertaining to co-ops.

The Illegal Unit / Illegal Multiple Dwelling, etc:

This type of case is found most often in Queens, Brooklyn and the Bronx. Many illegal units occupy the basements of two family houses, making them into what is called an Illegal Three. Sometimes two family houses are converted into four or more units. There are proper procedures whereby this may be done legally, but some Landlords skip all that and just rent out whatever they can.

How an Attorney Can Help:

An attorney can help you ascertain whether any of this applies to you. If it does then an attorney can raise this issue with the courts and there are many ramifications of this situation. A related situation is the one where a building which requires a Certificate of Occupancy doesn't have one, or if the Certificate of Occupancy has been violated by changes in the occupancy of the building.

Post-Foreclosure Eviction:

If you are the borrower being foreclosed on, you may want to visit ForeclosureFights.com for more information there. It may also be the case that your (former) Landlord was foreclosed on. Sometimes you may become aware of this during the pendency of the foreclosure, which can be a long process, or you may only learn of it afterward.
The property could wind up in the hands of the bank, a professional investor, someone looking to live there or the old owner could manage to keep the place.

How an Attorney Can Help:

If the foreclosure is pending BE CAREFUL WHO YOU PAY. Sometimes tenants are faced with conflicting rent demands from the person who rented them the place and other parties like a receiver or a bankruptcy trustee. A receiver can be appointed by a Court to collect the rent during the foreclosure. You need to be able to ascertain the legitimacy of his papers, and whether they are still valid. You don't want to pay the wrong person and wind up paying twice.
An attorney may be able to help obtain repairs, and keep heat and utilities on, during the foreclosure.
After the foreclosure you may still have rights depending on your status. Rent regulated tenants are in a strong position. Even if all you have is that you have been there more than 30 days, that is something. You need to have some evidence of your status and it is best to have at least some of it outside the place. If the new buyer changes the locks while you're at work (or if the co-op's doorman does not want to let you upstairs anymore) you may be able to get a judge to put you back in, but this will be complicated if all of the evidence you need to prove how long you've lived there is locked up in the place.
Just because someone says "I bought the place. Get out." may not mean that you have to get out. You may be able to fight them regardless of whether they are looking to move into the place personally or even if it is the co-op itself you are fighting.
If you are willing to get out, Investors and banks are often willing to pay "Cash for Keys" or perhaps you might need time to vacate. An attorney could help you negotiate terms for such settlements and make sure your rights are protected.
Lastly, if you really like the place and if you have financial resources, an attorney could help you make a proposal to buy the place, either as a Short Sale (buying from the borrower pre-foreclosure) or from the new owners post-foreclosure. You may even consider bidding at the foreclosure auction itself, though there are strict conditions associated with that.

Disputes Among Roommates:

These can get very personal and nasty. It is best if they can be resolved without litigation, but sometimes the other person isn't reasonable. Assuming one of you has a lease, that person(s) is the Tenant of Record. Someone else paying rent to the Tenant of Record is essentially a tenant of the tenant, or an undertenant. This is true in the case of roommates as well as sub-tenants.
Roommates have rights too. Roommates who have lived in a place for over 30 days cannot be locked out without being taken to Court. If they get locked out, they can bring an Illegal Lock-Out Proceeding against their "Landlord", the Tenant of Record. In Rent-Stabilized apartments roommates cannot be charged more than their proportionate share of the legal rent (there is a formula for calculating this). If the roommate is overcharged by the Tenant of Record then the roommate can sue for rent-overcharge. Of course, these roommates must be able to prove how long they have lived in the place and how much they have been paying. Such proof should be safely stored SOMEPLACE ELSE where opposing parties cannot get at it.
Any person having or claiming an interest in the space can answer an eviction case. You don't have to be the Tenant of Record. You don't have to be named as a Respondent.

How an Attorney Can Help:

An attorney can help you ascertain what your rights are and what steps you may need to take to secure them. An attorney might be able to help negotiate a settlement which may even be reduced to writing. It is best if the dispute can be resolved without going to Court and without the Landlord finding out. Often it winds up that the Landlord is the winner of these disputes, as the Tenant of Record and the roommate publicly throw accusations around. A rent overcharge on a rent-stabilized apartment is grounds for the Landlord to evict EVERYBODY.
If it does go to Court, you are even more in need of an attorney. Rather than the usual Landlord v. Tenant you have this complex multi-party free for all.
Sometimes, in rent-regulated apartments, the Landlord is willing to offer substantial cash to "buy-out" the Tenant of Record. As part of such deals the Tenant of Record must surrender the place "free of all occupants" and by a certain deadline. The roommate or subtenant, if they refuse to leave, can jeopardize the Tenant of Record's payday from the Landlord. This gets complicated. All interested parties should monitor the Court files of any cases involving the apartment, even if they are not named in the case. Buy-outs are written into stipulations which are typically filed with the Court.