The agreement was between the landlord & your roommate. Since you do not come under the definition of consumer, you are not bound to sign anything.Do not fall in this trap. Whatever you sign is likely to be used in later stages to prove that you were present at the scene of the fight. That will essentially empower the landlord (or the other neighbours who were involved in the fight) make you a party, witness or perpetrator in the fight in the event of a legal proceeding, if any.If you don't sign anything, you can wriggle out later saying that you had moved out before the fight, or present any other alibi.It also varies from state to state. For more clarity, you should consult whatever rent control act is there in your state (if any).