The claim that between law and morality there is a necessary
connection has many important variants, not all of them
conspicuous for their clarity. There are many possible interpretations
of the key terms 'necessary' and 'morality' and
these have not always been distinguished and separately considered
by either advocates or critics. The clearest, perhaps,
because it is the most extreme form of expression of this point
ofview, is that associated with the Thomist tradition ofNatural
Law. This comprises a twofold contention: first, that there
are certain principles of true morality or justice, discoverable
by human reason without the aid of revelation even though
they have a divine origin; secondly, that man-made laws which
conflict with these principles are not valid law. 'Lex iniusta
non est lex.' Other variants of this general point of view take
a different view of both the status of principles of morality
and of the consequences of conflict between law and morality.
Some conceive morality not as immutable principles of conduct
or as discoverable by reason, but as expressions of
human attitudes to conduct which may vary from society to
society or from individual to individual. Theories of this form
usually also hold that conflict between law and even the most
fundamental requirements of morality is not sufficient to deprive a rule of its status as law; they interpret the 'necessary'
connection between law and morality in a different way. They
claim that for a legal system to exist there must be a widely
diffused, though not necessarily universal, recognition of a
moral obligation to obey the law, even though this may be
overriden in particular cases by a stronger moral obligation
not to obey particular morally iniquitous laws.