be affected. * * * In other words, that parties
by entering into contracts may not estop the legislature from enacting
laws intended for the public good."[1713]

So, in an early case we find a State recording act upheld as applying to
deeds dated before the passage of the act.[1714] Later cases have
brought the police power in its more customary phases into contact with
private, as well as with public contracts. Lottery tickets, valid when
issued, were necessarily invalidated by legislation prohibiting the
lottery business;[1715] contracts for the sale of beer, valid when
entered into, were similarly nullified by a State prohibition law;[1716]
and contracts of employment were modified by later laws regarding the
liability of employers and workmen's compensation.[1717] Likewise a
contract between plaintiff and defendant did not prevent the State from
making the latter a concession which rendered the contract
worthless;[1718] nor did a contract as to rates between two railway
companies prevent the State from imposing different rates;[1719] nor did
a contract between a public utility company and a customer protect the
rates agreed upon from being superseded by those fixed by the
State.[1720] Similarly, a contract for the conveyance of water beyond
the limits of a State did not prevent the State from prohibiting such
conveyance.[1721]

Emergency Legislation.--But the most striking exertions of the
police power touching private contracts, as well as other private
interests, within recent years have been evoked by war and economic
depression. Thus in World War I the State of New York enacted a statute
which, declaring that a public emergency existed, forbade the
enforcement of covenants for the surrender of the possession of premises
on the expiration of leases, and wholly deprived for a period owners of
dwellings, including apartment and tenement houses, within the City of
New York and contiguous counties of possessory remedies for the eviction
from their premises of tenants in possession when the law took effect,
providing the latter were able and willing to pay a reasonable rent. In
answer to objections leveled against this legislation on the basis of
the obligation of contracts clause, the Court said: "But contracts are
made subject to this exercise of the power of the State when otherwise
justified, as we have held this to be."[1722] In a subsequent case,
however, the Court added that, while the declaration by the legi