This is in Albuquerque, NM.  Daughter and husband are being asked/told
to vacate apartment as their dog is ?oversize? as per the property
management company policy on dogs.   The manager was told when they
rented that it was over the size limit and the manager said it was OK.
 Neighbor complained.  Manager admits that person that complained is a
general pain but as the dog is oversized they or the dog must go. 
Manager is denying that he was told dog is oversize.  They were
offered a different apartment but none are available now then there is
no guarantee when and if one would be available.  As they will not get
rid of dog they must move and management company is charging for
breaking lease as they could choose to get rid of dog.   I feel since
they are being evicted they should not be held liable for breaking
lease and management for a different complex agrees with my view.

I am looking for any law that would back up my view.

Tenant rights vary from city to city.  Here is some general info for NM:

http://www.hud.gov/local/index.cfm?state=nm&topic=renting

There are renter's advocacy groups that will provide free legal
services, etc., in the event that they feel the tenants have been
mistreated.

It's too bad the tenants didn't receive anything in writing permitting
them to keep the dog.  Chances are the property manager is an employee
of a larger company that owns the property.  This person is probably
going by the book in order to avoid being fired for allowing the rule
violation in the first place.

It might not be a bad idea for the tenants to contact the property
owner him/herself and explain the situation and to offer to pay for
any damage that the dog does to the property (the main reason for a
dog size limit likely has to do with the wear and tear that a large
animal will cause on the property).  The property owner can make an
exception and will likely do so as long as his/her interests are taken
into consideration.