We have no doubt that the 1981 Tenancy Act passes muster under the contract clause as interpreted in Energy Reserves Group. First, it is doubtful that any impairment of a contractual relationship has occurred. The Tenancy Act only enlarged, for senior citizens and the disabled, a preexisting statutory tenancy which came into operation as a matter of law. Prior to the enactment of the Tenancy Act, New Jersey had already placed significant limitations upon the rights of owners of multiple dwellings to define the landlord-tenant relationship solely in terms of contract. The 1974 Anti-Eviction Act, which is not here challenged, provided that tenants could not be evicted; except for designated causes not relevant here, during the contractual term of a lease. See note 1 supra. Moreover, the Act mandated an eight-year extension of the lease — or a four-year extension coupled with a “hardship compensation payment” — if the landlord did not offer the tenant comparable housing. N.J. Stat.Ann. § 2A:18-61.2(g) (West Supp. 1983). Thus, beginning in 1974 the terms of the landlord-tenant relationship were specified to a large extent by statute. The Tenancy Act only operates to protect those statutory tenants whose relationship with their landlord has already become non-consensual by virtue of the Anti-Eviction Act. That is, the Tenancy Act simply enlarges the terms of a statutory tenancy already created by the Anti-Eviction Act. All of the plaintiffs acquired their interests in the Springfield complex after the Anti-Eviction Act went into effect. Such an enlargement of an already-regulated statutory tenancy is probably not an impairment at all. As the Supreme Court held in Veix v. Sixth Ward Building & Loan Ass’n, 310 U.S. 32, 38, 60 S.Ct. 792, 794, 84 L.Ed. 1061 (1940), “[w]hen he purchased into an enterprise already regulated in the particular to which he now objects, he purchased subject to further legislation upon the same topic.”