While political liberals make up a clear majority of Unitarian Universalists, the movement aspires to diversity, and officially welcomes congregants regardless of their political views. Politically conservative Unitarian Universalists point out that neither religious liberalism nor the Principles and Purposes of the UUA require liberal politics. Like the beliefs of Unitarian Universalists, politics are decided by individuals, not by congregations or the denomination. Several congregations have undertaken a series of organizational, procedural and practical steps to become acknowledged as a "Welcoming Congregation": a congregation which has taken specific steps to welcome and integrate gay, lesbian, bisexual & transgender (LGBT) members. Unitarian Universalist ministers perform same-sex unions and now same-sex marriages where legal (and sometimes when not, as a form of civil protest). On June 29, 1984, the Unitarian Universalists became the first major church "to approve religious blessings on homosexual unions." Unitarian Universalists have been in the forefront of the work to make same-sex marriages legal in their local states and provinces, as well as on the national level. Gay men, bisexuals, and lesbians are also regularly ordained as ministers, and a number of gay, bisexual, and lesbian ministers have, themselves, now become legally married to their partners. In May 2004, Arlington Street Church, in Boston, Massachusetts, was the site of the first state-sanctioned same-sex marriage in the United States. The official stance of the UUA is for the legalization of same-sex marriage—"Standing on the Side of Love". In 2004 UU minister Debra Haffner of The Religious Institute on Sexual Morality, Justice, and Healing published "An Open Letter on Religious Leaders on Marriage Equality" to affirm same-sex marriage from a multi-faith perspective. In December 2009, Washington, D.C. Mayor Adrian Fenty signed the bill to legalize same-sex marriage for the District of Columbia in All Souls Church, Unitarian (Washington, D.C.)  Unitarian Universalists for Polyamory Awareness engages Unitarian Universalist ministers and other leaders to educate them on polyamory. At the 2015 UUA General Assembly, the Association's non-discrimination rule was amended to include the category of "family and relationship structures"; the UUA has yet to take specific follow-up action on this, however. Many congregations are heavily involved in projects and efforts aimed at supporting environmental causes and sustainability. These are often termed "seventh principle" activities because of the seventh principle quoted above.