Sam Himmelstein, a rental lawyer, says an oral agreement is always a binding agreement. Depending on your specific circumstances, your landlord can`t just increase your rent. But it`s important to know how the law applies to your situation. Second, a written lease is established in order to avoid misinterpretations and to accept the main points of the lease. Thanks to a well-crafted rental agreement that outlines the responsibilities of the tenant and landlord, everyone knows where they are and what is expected, and all disputes in the wider field would be avoided.