The primary objective of giving power to the state to criminalise human conduct is to maintain order in society. There is an assumption that where an individual might cause harm to another, there is an inherent possibility of society disorder if there is no mechanism for the control of such behaviour through the machinery of the state. Criminal laws serve the function of controling such harmful behaviour.
S.377A of the Penal Code criminalises consensual sexual relations between 2 men even though no harm may be caused by one to the other.
s.375 of the Penal Code exempts a man from liability where he has raped his wife. Here, there is harm caused by an individual to another. But, the state stands aside and exempts the offending individual from liability.
I know that the debate over homosexual intercourse and marital rape has been clouded by too many arguments about traditional 'morality', religious perceptions and notions of the so-called traditional marital relations. But, we are not talking about issues pertaining to morally acceptable behaviour when we deal with criminal offences. We should be dealing with how the state should go about its job in maintining order. If we acknowledge that the primary objective of criminal law is to prevent individuals from acting in a manner that would cause harm to others, then s.377A and s.375 are completely at odds with that primary objective.
John Stuart Mill in his essay, On Liberty, propounds on the 'harm' principle:
That principle is, that the sole end for which mankind are warranted, individually or collectively in interfering with the liberty of action of any of their number, is self-protection. That the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinions of others, to do so would be wise, or even right. These are good reasons for remonstrating with him, or reasoning with him, or persuading him, or entreating him, but not for compelling him, or visiting him with any evil, in case he do otherwise. To justify that, the conduct from which it is desired to deter him must be calculated to produce evil to some one else. The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.