First set of laws imposed on humans
Initially, the first set of laws imposed on humans was the laws of the land created by God. These laws were created to established order, punish wrong doings and promote equality. The Ten Commandments written in the Bible were rules which governed what a person should and should not do. Questionably, these rules may have been directed towards Jews and other persons of a religious faith; however, they have evolved in a wider sense and are used as moral guidelines throughout today’s societies. 
What is criminal law?
The criminal law addresses offences such as murder, assault, theft, litter offences, crimes against public morals and traffic violations. These offences are crimes that when committed affect society as a whole. It is a very broad scope of law and its exact purpose is difficult to define, however, the American Law Institute Model Penal code  provides a list of a few functions that are agreed upon, these include: 
Deterring persons from doing acts that harm others or society;
Setting out the conditions under which people who have performed such acts will be punished;
Providing some guidance on the kinds of behaviour which are seen by society as acceptable.
To differentiate on reasonable grounds between serious and minor offences.
These functions highlight the importance of criminalizing offences and of individual autonomy establishing a perfect balance between the two. Criminal law is vital to the running of a society and that society determines what is criminal behaviour. These values and culture may have different origins, some religious and some social, however the disputed conducts are usually agreed upon. Crimes are either categorized as mala in se which is wrongs judged by society or mala prohibita which is wrongs prohibited by statute. The main feature of mala in se crimes is that they are considered crimes because of what the public feel is immoral ‘on its face’ and needs no justification.  This is where moral principles become involved in criminal law.
What are moral principles?
Moral principles have always been seen as important to society, they establish acceptable practices and guidelines to be followed by the pubic in efforts to maintain a controlled environment providing rules as to what is morally right or wrong and what should or should not be done. According to Devlin in the enforcement of morals (1965), morality is vital to social order, without morals a society cannot exist.  These standards regulate right and wrong conduct and are known as normative ethics. There are three types of normative ethical theories, they are as follows: Virtue ethics which focuses on the nature of a person. Deontology which argues that a decision should be made based on personal responsibilities and the rights of others and Consequentialism which argues that a decision would be considered moral or immoral depending on the results it brings about. These theories will be mentioned throughout this paper.
Criminal law equals morality
There have been ongoing arguments as to whether criminal enforcement should play a part in enforcing morality. Some believe there is a vital connection between the two and that the function of criminal law is simply to enforce such principles.
Moral principles help shape law. Arguably, “law rests on a stable and identifiable community sentiment of what is moral and right".  Having these principles in a society provides structure, a sense of individual responsibility and safety. This is supported by Lord Denning as he stated “standards and morals are the concern of the law... whether done in private or in public... our legal system is concerned with laying down right standards of behaviour, what people should or should not do." 
Guidelines facilitate stability and societies need such structure to avoid uproar and/or imbalances. Society is built on cultural norms and practices that shape individuals actions. Without these common values a society can break down. Devlin states:
“society means a community of ideas; without shared ideas on politics, morals and ethics no society can exist ... history shows that the loosening of moral bonds is often the first stage of disintegration." 
For example, a traditional family consist of a father (man), a mother (woman) and children. However, the practice of homosexuality (although arguably a private vice) destroys the fabric of traditional families and can subsequently affect birth rates, considering homosexuals cannot reproduce. Devlin disagrees with this practice and feels that it should be illegal because it threatens the decency of society. Anything that does such is considered immoral and wrong. Although Hart has contrary views to Devlin, he to agree that “some shared morality is essential to the existence of society..."  and enforcing such moral principles help maintain structure.
For the most part, every individual has some type of morals whether they derive from a religious or social background or the law itself. “Morality... is something which is both within the individual and which encapsulates him by virtue of his membership of society."  It is understood that these morals are in line with the majority of society’s views of what is right or wrong, enforcing these principles would instil fear in members of the public of becoming outcasts if these principles are not followed. The public should abide by what is morally accepted adopting it as a norm. This is associated with the Deontology principle as persons should abide by moral guidelines and are obligated to follow them upholding his or her duty to himself and society.
Some crimes against public morals may be considered private (drunkenness); however, they can also have an effect on the public. What an individual do behind closed doors is arguably his business, but what happens when the affects of what was done is brought in public? “There are certain standards of behaviour or moral principles which society requires to be observed; and the breach of them is an offence not merely against the person who is injured but against society as a whole."  As for every action there is a reaction, for example, a man may drink within the comfort of his own home, but when he leaves his house in a drunken state he places the public at risk to his behaviour. He may be obnoxious, abrasive or may go to the extreme and drive drunk, all potentially harming victims and affecting society.
The law plays apart in enforcing moral principles by implementing laws that protect society such as prohibiting sexual acts with girls under the age of 16 before or outside of marriage. This prohibition is put in place to protect adolescent females from complications that can occur during pregnancy and childbirth.  The purpose of moral laws is for the safety and health of the entire public. Other popular considerations that may be behind this moral law are risks of diseases and abortion (another big moral issue). However, this function of the law can be viewed as utilitarianism as the law tries to prevent the predicted consequences of an action which are in this case, complications that can occur with a girl under 16. Utilitarianism is about a decision being made for the greatest good for the greatest number. Areas that are not considered the laws business are considered within moral law to protect and benefit society as a whole. One can only suggest that the criminal law attempts to enforce moral principles in efforts to keep a society going with structure, responsibility and safety. However, it is argued that this type of paternalistic approach with regards to moral principles over a society is overstressed and somewhat unnecessary.
Criminal law minus morality
The Wolfenden committee argue that the function of the criminal law is:
“... not to intervene in the private lives of citizens, or to seek to enforce any particular pattern of behaviour." 
John Stuart- Mills agreed with him and stated that:
“the only purpose for which power can rightfully be exercised over any member of a civilised community, against his will, is to prevent harm to others... his own good either physically or moral is not sufficient warrant." 
Debatably, the function of criminal law is not primarily or solely to enforce moral principles; it is simply to ensure that the health and safety of the public is secure. Mills argue that the primary function of the criminal law is to prevent individuals from harming others. By the criminal law trying to enforce such principles they are acting ‘ultra vires’ (beyond the scope of their powers). According to William Blackstone (1769):
“all crimes ought... to be estimated merely according to mischief’s which they produce in civil society... private vices... cannot be, the object of any municipal law..." 
Additionally, the law places unreasonable restrictions on members of the public, thus, violating a number of articles under the Human Rights Act 1998 (HRA) and the European Convention of Human Rights 1950 (ECHR).
The only laws that should be enforced are those on the law books, anything beyond this is unacceptable and intolerable. Punishing persons for violating norms that are not on the law books will open a flood gate of questions and uncertainty. For example, who decides what is moral from immoral? Devlin argues that this is the job of a reasonable man, but who and what determines a reasonable man? If society makes this decision, can the criminalization of certain public morals stop when society changes its views on those same principles? Hart saw a flaw with Devlin’s “social disintegration thesis."  Devlin suggested that a society’s moral principles must remain the same to prevent it from breaking down. However, Hart believes that change can occur within society’s morals without disfiguration taking place.  The belief in certain moral principles changes and what was once immoral is now with time, being accepted within societies. For example, opposition to same sex marriages has declined by almost 20% since 1996.  Additionally, actions which were once criminally liable years ago may be now be considered innocent. For example, suicide, the taking of one’s own life was once considered a crime until 1961 when the crime was ‘abrogated’.  According to Joel Feinberg, not all immoral conduct is harmful to society, so what happens to acts that go against public norms, but the courts are still lenient? Or acts that can be viewed as either moral or immoral depending on the circumstances surrounding it?  For example, abortion, this is a highly controversial issue, but is it still discriminated against when the woman is a victim rather than an offender, a victim of rape or has severe health complications? Additionally, allowing the criminal law to enforce moral principles can lead to issues of ‘ultra vires’. How can the law legislate on matters they have no authority to? These matters should be left to Parliament and the doctrine of separation of powers should be reinforced.
“Morality in relation to the law constitutes an external environment which interacts with the law-making process... laws tend to be based upon value-loaded information which percolates to the law-makers (whose own individual values have a disproportionate influence upon the process)." 
In other words, although ‘judges are said to be guardians of the law’ their moral beliefs do influence the law to a certain extent and decisions may be based on morality rather than strictly law.
The HRA and ECHR were both formed to protect human rights and freedoms which is the one thing that is equal to everyone. Mill believed that individuals should be given the highest level of freedom and independence that is ‘consistent with the rights of others’.  It is argued that the “criminal law is an improper instrument for regulating the private moral conduct of individuals that caused no direct harm to others.  By the criminal law enforcing moral principles on the public it breaches the following articles: the right to liberty (article 5), the right to privacy (article 8), freedom of conscience (article 9), freedom of expression (article 10), freedom of assembly (article 11) and discrimination (article 14).  Discriminately, a certain class of living, a particular religion or career choices are not enforced within societies, therefore, criminal law should not involve itself with matters that does not affect society. According to Michel Foucault, “the sole purpose of existence is to be your “true self"... to accomplish this one must constantly struggle against the ‘disciplines’ of society."  To allow the law to control you is to limit yourself from achieving your full potential. In order to be considered free and fully enjoy life Mill believes that one must be able to:
1) have liberty of thought and feeling; absolute freedom of opinion and sentiment on all subjects, practical or speculative, scientific, moral, or theological.
2) have liberty to plan life to suit your own character; of doing as we like, subject to such consequences as may follow.
3) have freedom to unite and combine with persons; person of combination being of full age, and not forced or deceived.
Mills believes that if any of these liberties are restricted in a society then it is not “wholly" free. “The only freedom which deserves the name, is that of pursuing our own good in our own way, so long as we do not attempt to deprive others of theirs or impede their efforts to obtain it..." p .27  This view can be considered as autonomy based interpretation where persons are treated as equals which allows them to pursue their ends whatever they may be. Furthermore, “strong moral disapproval does not necessarily imply that there should be a law."  Therefore, criminal law should enforce matters that directly affect society and should not concern itself with issues of public opinion that should not be considered criminal.
Whether and why we need dialogue and debate before we decide the criminal enforcement of moral principles?
Moral principles are created by the public views and feelings on social issues. According to Devlin, “the morals of society are those standards of conduct of which the reasonable man approves."  It is the majority in the public that decides what is morally acceptable in their society. “Individuals and groups seek to persuade others that their own morality is, or should become, part of the shared morality embodied in a legal rule."  The public’s voice is either heard through public forums, strikes or protests. It is argued that only certain voices are heard and the ideas and opinions of the less fortunate are drowned by those in higher classes. Foucault argues that “the elite in society dominate and control the society..."  Despite this hi-cup, it is vital to inform the public by dialogue or debate on actions and behaviours that are acceptable and those that are criminally liable before criminal enforcement takes place. This prevents confusion about the nature and quality of the act. “Public opinion about criminal justice is at times misinformed, and largely as a result of those misperceptions, the public has low levels of confidence in the criminal justice system." Additionally, “after learning about a criminal justice issue and having a chance to deliberate over it, the public is much more open to change than conventional wisdom would suggest." 
Some may argue that matters of criminal enforcement are personal and the decision should solely be left to parliament. To some degree this may be true as it is Parliament’s job to approve new laws. The government may introduce new plans or changes to laws, but before they become law the House of Commons and House of Lords must debate and vote on the proposals.  In the cases of Shaw v DPP  AC 220 and Knuller v DPP  AC 435 both defendants were charge with ‘conspiracy to corrupt public morals’, they argued that they could not be convicted because no such crime existed, however, the House of Lords addressed this argument by making the conviction a new crime. The law Lords ‘doubted’ the correctness of their decision in Shaw, but still followed it in deciding Knuller. Lord Reid stated in the dissenting judgement that “parliament is the... only proper place, to settle... immorality cases."  Therefore, it can be said that the only debate necessary is the one between the two houses. However, there have been circumstances where the public involvement has had an effect on law as “the law influences public opinion and, conversely, public opinion influences the law..."  For example, the public felt that criminal law should do more to protect society against sex offenders, because of this, measures regarding “sex offenders registration, community notification, and involuntary civil commitment for some sex offenders" were put in place. 
Arguments about morality have played a part in several issues consequently shaping the law. The public’s opinion, the changed attitude in society, campaigns by the media and liberal pressure groups are said to be “the principal reasons for the abolition of the death penalty in Britain."  Morality makes it immoral to take a person’s life and not even the law possessed the power to contradict that moral principle. Morality has also shaped the law in issues including: “human sexuality, divorce, legal status and international law..."  Public opinion and morality has a played a part in the decision to free the Lockerbie bomber because of his ailment. It was stated by Scottish Justice Secretary Kenny MacAskill, that "Compassion and mercy are about upholding the beliefs that we seek to live by, remaining true to our values as a people - no matter the severity of the provocation or the atrocity perpetrated."  In other words, it would have been immoral to keep a sick man who was expected to die within three months incarcerated and therefore, the moral thing to do was to grant his release from jail.
To conclude, the criminal law serves many purposes in society. Enforcing moral principles in some crimes is not the only function of criminal law, but in doing so it provides structure, a sense of individual responsibility and safety. On the other hand, human rights are restricted, flood gates are opened and criminal law is deciding on matters that are outside the scope of their powers.  Therefore, the law should continue to protect society from any harm or potential danger, but should also preserve the rights of individuals within societies, maintaining a perfect balance between the two. Consequently, the statement should read: in a number of crimes [one] of the functions of criminal law is to enforce moral principles [among others].