Q: I rented a condo last summer, planning to stay for a year. No formal lease was signed. The landlord told me in the winter that he was having trouble making his mortgage payments, and sure enough, the place was sold in April and I was given a month to move. I moved out, but wonder if I could have protested. –Jim F.
A: The key to your question lies not in the absence of a "formal lease." In fact, the phrase "formal lease" has no legal meaning. Instead, the question is what the parties — you and the landlord — intended when you reached your agreement.
If you both thought that the rental was for a year, but didn’t reduce that understanding to writing, that simply means that you had an oral lease, which is enforceable in all states for up to one year.
An oral lease, for sure, is harder to prove — if you or the landlord were to claim that the understanding was for a month-to-month deal, for example, you’d be in the uncomfortable position of having to rely on your memories to prove your positions (the classic "he said — he said").