Why wouldn't it be enforceable? Leases needn't be notarized.
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So long as it was executed by two parties with authority it need not be verified by Notary Public.
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I believe you do have a lease. However, I do not know why you are asking the question. It is complicated because the landlord is you and your husband and the tenant is your son if I understand you. Did your husband authorize you to sign the lease or sign it himself? Is your son trying to get out of the lease? To be safe and allow you to enter into a new lease for the property you and your son should probably sign a paper that says the lease is hereby terminated and reference the property and date of the lease. If you want to sue your son it is more problematic because your husband must join in the suit and the issue I raised about whether he signed the lease or authorized you to sign it is important. I think your husband also has to sign the termination of the lease if he approved it originally.