Definition of marriage
The classic legal definition of marriage can be found in Hyde v Hyde and Woodmansee,  where Lord Penzance defined marriage as the ‘voluntary union for life of one man and one woman, to the exclusion of all others’.  This has been enshrined in the Matrimonial Causes Act (MCA) 1973 s.11(c), where a marriage is void when the parties are not respectively male and female. This has also been re-affirmed by the House of Lords (HL) in Ghaidan v Godin-Mendoza,  where Lord Millet stated that in a marriage, ‘a man’s spouse must be a woman; a woman’s spouse must be a man’. 
However, in Goodwin v United Kingdom (UK),  the European Court on Human Rights held that a transsexual, which was prevented from marrying a person of her choice because her legal gender fixed at birth which was no longer reflected her identity, was violating Articles 8 and 12 of the European Convention on Human Rights (ECHR), namely right to respect for private and family life, and right to marry respectively. Subsequently, the HL in Bellinger v Bellinger,  declared that s.11(c) of the MCA 1973 which prohibits a transsexual person marrying in her declared sex was incompatible with Articles 8 and 12 of the ECHR. This has led the government enacting the Gender Recognition Act 2004, and marriage is no longer restricted to those who were born respectively male and female.
Nevertheless, same-sex partners are prohibited to marry.  They can, however, under the Civil Partnership Act (CPA) 2004 s.1(1), enter into civil partnership. In Wilkinson v Kitzinger,  a same-sex couple was married in accordance to the Canadian law and wanted to seek recognition of their marriage in UK. The court refused to recognise the same-sex marriage and held that there was no violation of Articles 8 and 12 of the ECHR. Sir Mark Potter P stated that the ‘right to marry’ under Article 12 refers to the traditional sense, namely as a marriage between a man and a woman,  and the rights of the same-sex partners under CPA 2004 are similar to the rights of heterosexual partners through marriage. 
There are, however, some States which have already recognised same-sex marriage.  Recently, the UK government has signalled the possibility of allowing same-sex marriages.  The question now is: Should same-sex couples be entitled to marry?
One of the reasons that people get married is because of love.  As pointed out by Heimbach, marriage is ‘how society affirms a decision lovers make to care for each other through good times and bad’.  Homosexuals are human too. They love each other as deeply and sincerely as heterosexual partners.
Besides, La Forest J in the Egan v Canada,  stated that sexual orientation is ‘a deeply personal characteristic that is either unchangeable or changeable only at unacceptable personal costs’,  and held that the discrimination on the grounds of sexual orientation was unconstitutional. The Canadian courts have, in a number of cases,  ruled that the exclusion of same-sex couple to marry was a form of discrimination and unconstitutional. Similarly, Chief District Court Judge, Vaughn R Walker, in Perry v Schwarzenegger,  held that the California Proposition 8 which only allows the heterosexual couples to marry was sexual orientation discrimination and unconstitutional, and President Obama had directed the government to stop defending the law banning federal recognition of same-sex marriages approved by states. 
Moreover, unlike marriage, ss.2(5) and (6) of the CPA 2004 prohibit the use of religious premises and services in a civil partnership registration. Cretney stated that the purpose of refusing the same-sex marriage in Christian church is because some may still regarded as sinful,  but some churches are indeed willing to solemnize same-sex marriages.  As Readhead pointed out, some of the same-sex couples wanted to have religious element in the civil partnership registration.  Research had shown that religion is an important factor for homosexual couple.  They want to get married in front of people, in front of God, and in front of friends. 
As mentioned above, the rights granted to the heterosexual couples by the CPA 2004 are similar to the rights granted to the heterosexual couples through marriage. Gilbert stated that the denying of same-sex couples access to marriage implies that their relationships as inferior,  and they no longer want to be ‘separate but equal’ anymore.  In addition, the Ontario Court of Appeal in Halpern v Canada,  stated that the exclusion of the same-sex couples from marriage is an offence to the dignity of the persons in same-sex relationships. 
The next issue to be considered is whether should heterosexual couple have the rights to enter civil partnership. Section 3(1)(a) of the CPA 2004 states that those who are not same-sex are not eligible to register civil partnership. The main purpose of the UK Parliament enacting the CPA 2004 is to remove criminal outlawing same-sex activities,  and to give recognitions, rights and responsibilities to the same-sex couples. 
Tatchell argued that in a ‘democratic society, everyone should all be equal before the law’.  He continued to state that ‘everyone should have a choice, either a civil marriage or civil, whichever they prefer’.  Since everyone should all be equal before the law, the CPA 2004 should be repealed and same-sex partners should be allowed to marry under the MCA 1973. As pointed out by Marrin, it is not desirable and is wrong if the CPA 2004 were to be extended the marriage privileges and protections to the unmarried couples. 
In conclusion, Lord Penzance’s statement above should no longer reflect today’s marriages. As pointed out above, it is unconstitutional and is discriminating homosexuals by prohibiting same-sex couples to marry. Thus, marriage should no longer confined to heterosexual couples, but it should extend to homosexual couples. The CPA 2004 should not be used by heterosexual partners and it should be repealed as discussed above.