History of same-sex unions
Although state-recognized same-sex unions are becoming more accepted, there is a long history of same-sex unions around the world. Various types of same-sex unions have existed, ranging from informal, unsanctioned, and temporary relationships to highly ritualized unions that have included marriage.
Classical Europe, Middle East and China
While it is a relatively new practice that same-sex couples are being granted the same form of legal marital recognition as commonly used by mixed-sexed couples, there is a long history of recorded same-sex unions around the world. Various types of same-sex unions have existed, ranging from informal, unsanctioned relationships to highly ritualized unions.
A same-sex union was known in Ancient Greece and Rome, ancient Mesopotamia, in some regions of China, such as Fujian province, and at certain times in ancient European history. These same-sex unions continued until Christianity became the official religion of the Roman Empire. A law in the Theodosian Code (C. Th. 9.7.3) was issued in 342 AD by the Christian emperors Constantius II and Constans, which prohibited same-sex marriage in ancient Rome and ordered that those who were so married were to be executed. 
Same-sex marital practices and rituals were more recognized in Mesopotamia than in ancient Egypt. In the ancient Assyrian society, there was nothing amiss with homosexual love between men. Some ancient religious Assyrian texts contain prayers for divine blessings on homosexual relationships. The Almanac of Incantations contained prayers favoring on an equal basis the love of a man for a woman and of a man for man.
In the southern Chinese province of Fujian, through the Ming dynasty period, females would bind themselves in contracts to younger females in elaborate ceremonies. Males also entered similar arrangements. This type of arrangement was also similar in ancient European history.
An example of egalitarian male domestic partnership from the early Zhou Dynasty period of China is recorded in the story of Pan Zhang & Wang Zhongxian. While the relationship was clearly approved by the wider community, and was compared to heterosexual marriage, it did not involve a religious ceremony binding the couple.
Some early Western societies integrated same-sex relationships. The practice of same-sex love in ancient Greece often took the form of pederasty, which was limited in duration and in many cases co-existed with marriage. Documented cases in this region claimed these unions were temporary pederastic relationships. These unions created a moral dilemma for the Greeks and were not universally accepted.
Amongst the Romans, there were instances of same-sex marriages being performed, as evidenced by emperors Nero who married an unwilling young boy  and (possibly - though it is doubted by many historians) the child emperor Elagabalus, who both supposedly married a man, and by its outlaw in 342 AD in the Theodosian Code, but the exact intent of the law and its relation to social practice is unclear, as only a few examples of same-sex marriage in that culture exist.
In Hellenic Greece, the pederastic relationships between Greek men (erastes) and youths (eromenos) were similar to marriage in that the age of the youth was similar to the age at which women married (the mid-teens, though in some city states, as young as age seven), and the relationship could only be undertaken with the consent of the father. This consent, just as in the case of a daughter's marriage, was contingent on the suitor's social standing. The relationship consisted of very specific social and religious responsibilities and also had a sexual component. Unlike marriage, however, a pederastic relation was temporary and ended when the boy turned seventeen.
At the same time, many of these relationships might be more clearly understood as mentoring relationships between adult men and young boys rather than an analog of marriage. This is particularly true in the case of Sparta, where the relationship was intended to further a young boy's military training. While the relationship was generally lifelong and of profound emotional significance to the participants, it was not considered marriage by contemporary culture, and the relationship continued even after participants reached age 20 and married women, as was expected in the culture.
Numerous examples of same sex unions among peers, not age-structured, are found in Ancient Greek writings. Famous Greek couples in same sex relationships include Harmodius and Aristogiton, Pelopidas and Epaminondas and Alexander and Bogoas. However in none of these same sex unions is the Greek word for "marriage" ever mentioned. The Romans appear to have been the first to perform same sex marriages.
At least two of the Roman Emperors were in same-sex unions; and in fact, thirteen out of the first fourteen Roman Emperors held to be bisexual or exclusively homosexual. The first Roman emperor to have married a man was Nero, who is reported to have married two other men on different occasions. First with one of his freedman, Pythagoras, to whom Nero took the role of the bride, and later as a groom Nero married a young boy to replace his young teenage concubine who he had killed  named Sporus in a very public ceremony... with all the solemnities of matrimony, and lived with him as his spouse A friend gave the "bride" away "as required by law." The marriage was celebrated separately in both Greece and Rome in extravagant public ceremonies. The Child emperor Elagabalus Emperor Elagabalus referred to his chariot driver, a blond slave from Caria named Hierocles, as his husband. He also married an athlete named Zoticus in a lavish public ceremony in Rome amidst the rejoicings of the citizens.
It should be noted, however, that conubium existed only between a civis Romanus and a civis Romana (that is, between a male Roman citizen and a female Roman citizen), so that a marriage between two Roman males (or with a slave) would have no legal standing in Roman law (apart, presumably, from the arbitrary will of the emperor in the two aforementioned cases).
When a man “marries” in the manner of a woman, a “woman” about to renounce men, what does he wish, when sex has lost its significance; when the crime is one which it is not profitable to know; when Venus is changed into another form; when love is sought and not found? We order the statutes to arise, the laws to be armed with an avenging sword, that those infamous persons who are now, or who hereafter may be, guilty may be subjected to exquisite punishment. (Theodosian Code 9.7.3) 
According to Robin Lane Fox, among the unusual customs of the isolated oasis of Siwa (now Egypt, once Libya), one of great antiquity which survived to the 20th century was male homosexuality and same-sex marriage.
Policy of the early Christian Church and Middle Ages
As did other philosophies and religions of the time, increasingly influential Christianity promoted marriage for procreative purposes. The teachings of the Talmud and Torah, and the Bible, were seen as specifically prohibiting the practices as contrary to nature and the will of the Creator, and a moral shortcoming. Even after the passing of the Theodosian code the Christian emperors continued to collect taxes on male prostitutes until the reign of Anastasius (491–518). In the year 390, the Christian emperors Valentinian II, Theodoisus and Arcadius declared homosexual sex to be illegal and those who were guilty of it were condemned to be burned alive in front of the public. The Christian emperor Justinian (527–565) made homosexuals a scapegoat for problems such as "famines, earthquakes, and pestilences." While homosexuality was tolerated in pre-Christian Rome, it was still nonetheless controversial. For example, arguments against same-sex relationships were included in Plutarch's Moralia.
In pre-Christian Rome and Greece, there had been some debate on which form of sexuality was preferable. While many people seemed to not oppose bisexuality, there were those who preferred to be exclusively heterosexual or homosexual. For example, a debate between homosexual and heterosexual love was included in Plutarch's Moralia.
After the Middle Ages in Europe, same-sex relationships were increasingly frowned upon and banned in many countries by the Church or the state. Nevertheless, Historian John Boswell argued that Adelphopoiesis, or brother-making, represented an early form of religious same-sex marriage in the Orthodox church. Alan Bray saw the rite of Ordo ad fratres faciendum ("Order for the making of brothers") as serving the same purpose in the medieval Roman Catholic Church. However, the historicity of Boswell's interpretation of the ceremony is contested by the Greek Orthodox Church, and his scholarship critiqued as being of dubious quality by scholars such as Robin Darling Young, Associate Professor of Theology at the Catholic University of America.
In late medieval France, it is possible the practice of entering a legal contract of "enbrotherment" (affrèrement) provided a vehicle for civil unions between unrelated male adults who pledged to live together sharing ‘un pain, un vin, et une bourse’ – one bread, one wine, and one purse. This legal category may represent one of the earliest forms of sanctioned same-sex unions.
While the church father, Augustine of Hippo, presented marriage as an important sacrament of the Christian Church in the 5th century CE, it wasn't until the “Sentences” of Peter Lombard, in the middle of the 12th century, that marriage became a part of the seven sacraments of the Catholic Christian Church.
A same-sex marriage between the two men Pedro Díaz and Muño Vandilaz in the Galician municipality of Rairiz de Veiga in Spain occurred on 16 April 1061. They were married by a priest at a small chapel. The historic documents about the church wedding were found at Monastery of San Salvador de Celanova.
In the 20th and 21st centuries various types of same-sex unions have come to be legalized. Same-sex marriage is currently legal in fourteen European countries: Belgium, Denmark, Iceland, the Netherlands, Norway, Portugal, Spain, France and Sweden; Luxembourg, Finland and the United Kingdom are currently in the process of legalization. Politicians in the United Kingdom have expressed their intention to promote legislation to allow same-sex marriage. Other types of recognition for same-sex unions (civil unions or registered partnerships) are as of 2012 legal in the following European countries: Andorra, Austria, Czech Republic, Denmark, Finland, France, Germany, Hungary, Ireland, Isle of Man, Jersey, Liechtenstein, Luxembourg, Slovenia, Switzerland and the United Kingdom.
On July 20, 2005, Canada became the fourth country in the world and the first country in the Americas to legalize same-sex marriage nationwide with the enactment of the Civil Marriage Act which provided a gender-neutral marriage definition. Court decisions, starting in 2003, each already legalized same-sex marriage in eight out of ten provinces and one of three territories, whose residents comprised about 90% of Canada's population. Before passage of the Act, more than 3,000 same-sex couples had already married in those areas. Most legal benefits commonly associated with marriage had been extended to cohabiting same-sex couples since 1999.
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- He killed himself a few years afterwards and Nero "castrated" him q.v., Suetonius Nero 28; Dio Cassius Epitome 62.28 Old Translation of passage at: http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Cassius_Dio/62*.html
- Eskridge, William N. (Oct 1993). "A History of Same-Sex Marriage". Virginia Law Review 79 (7). "[The] Romans may have accorded some same sex relationships the legal or cultural status of marriages [...]"
- Johansson, Warren & Percy, William A. "Homosexuality in the Middle Ages". pp. N47. Retrieved 2007-01-21. "For example, Nero, who was married to a woman, simultaneously became the bride of a freedman and the husband of a eunuch."
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- Theodosian Code 9.7.3: "When a man “marries” in the manner of a woman, a “woman” about to renounce men, what does he wish, when sex has lost its significance; when the crime is one which it is not profitable to know; when Venus is changed into another form; when love is sought and not found? We order the statutes to arise, the laws to be armed with an avenging sword, that those infamous persons who are now, or who hereafter may be, guilty may be subjected to exquisite punishment.
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- Corbett, The Roman Law of Marriage (Oxford, 1969), pp. 24–28; Treggiari, Roman Marriage (Oxford, 1991), pp. 43–49.; "Marriages where the partners had conubium were marriages valid in Roman law (iusta matrimonia)" [Treggiari, p. 49]. Compare Ulpian (Tituli Ulpiani 5.3–5: "Conubium is the capacity to marry a wife in Roman law. Roman citizens have conubium with Roman citizens, but with Latins and foreigners only if the privilege was granted. There is no conubium with slaves"; compare also Gaius (Institutionum 1:55–56, 67, 76–80).
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- Eskridge, William N. (Oct 1993). "A History of Same-Sex Marriage". Virginia Law Review 79 (7). "But other, non-Christian traditions in Roman society—Stoicism, Neo-Platonism and Manicheanism—similarly urged that "intercourse was supposed to take place only so as to produce children. The couple must not make love for the sake of pleasure alone.""
- (Theodosian Code 9.7.6): All persons who have the shameful custom of condemning a man's body, acting the part of a woman's to the sufferance of alien sex (for they appear not to be different from women), shall expiate a crime of this kind in avenging flames in the sight of the people.
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- Eskridge, William N. (Oct 1993). "A History of Same-Sex Marriage". Virginia Law Review 79 (7). "While the statute [that prohibited same-sex marriage in ancient Rome] reinforces the impression that same-sex marriages were not uncommon in the Roman Empire, it also evidences an anxiety about same-sex unions that antedated the 4th century. At the end of the 2nd century, for example, Plutarch's Moralia included a dialogue filled with invective both for and against same-sex relationships, suggesting that their propriety was a matter of some controversy. A subsequent anonymous dialogue entitled Affairs of the Heart was sympathetic to same-sex relationships but sharply distinguished them from marriage."
- Eskridge, William N. (Oct 1993). "A History of Same-Sex Marriage". Virginia Law Review 79 (7). "While the statute [that prohibited same-sex marriage in ancient Rome] reinforces the impression that same-sex marriages were not uncommon in the Roman Empire, it also evidences an anxiety about same-sex unions that antedated the 4th century. At the end of the 2nd century, for example, Plutarch's Moralia included a debate on the merits of Greek pederasty versus heterosexual marriage. The debate points out the good and bad aspects of both forms of love in a debate between proponents of both types of relationships. A subsequent anonymous dialogue entitled Affairs of the Heart was sympathetic to same-sex relationships but sharply distinguished them from marriage."
- Young, Robin Darling (November 1994). "Gay Marriage: Reimagining Church History". First Things (47): 43–48.
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