“This morning, the Supreme Court recognized that the Constitution guarantees marriage equality. In doing so, they’ve reaffirmed that all Americans are entitled to the equal protection of the law. That all people should be treated equally, regardless of who they are or who they love. […] This ruling will strengthen all of our communities by offering to all loving same-sex couples the dignity of marriage across this great land.”

Letter to Jacob De La Motta (August 1820), Manuscript Division, Papers of James Madison http://www.jewishvirtuallibrary.org/jsource/loc/madison.html
1820s
Context: Equal laws protecting equal rights, are found as they ought to be presumed, the best guarantee of loyalty, and love of country; as well as best calculated to cherish that mutual respect and good will among citizens of every religious denomination which are necessary to social harmony and most favorable to the advancement of truth.
Context: Among the features peculiar to the political system of the United States is the perfect equality of rights which it secures to every religious sect. And it is particularly pleasing to observe in the good citizenship of such as have been most distrusted and oppressed elsewhere, a happy illustration of the safety and success of this experiment of a just and benignant policy. Equal laws protecting equal rights, are found as they ought to be presumed, the best guarantee of loyalty, and love of country; as well as best calculated to cherish that mutual respect and good will among citizens of every religious denomination which are necessary to social harmony and most favorable to the advancement of truth.

Source: Flatland: A Romance of Many Dimensions (1884), PART I: THIS WORLD, Chapter 9. Of the Universal Colour Bill
Context: The Art of Sight Recognition, being no longer needed, was no longer practised; and the studies of Geometry, Statics, Kinetics, and other kindred subjects, came soon to be considered superfluous, and fell into disrespect and neglect even at our University. The inferior Art of Feeling speedily experienced the same fate at our Elementary Schools.... Year by year the Soldiers and Artisans began more vehemently to assert — and with increasing truth — that there was no great difference between them and the very highest class of Polygons, now that they were raised to an equality with the latter, and enabled to grapple with all the difficulties and solve all the problems of life, whether Statical or Kinetical, by the simple process of Colour Recognition. Not content with the natural neglect into which Sight Recognition was falling, they began boldly to demand the legal prohibition of all "monopolizing and aristocratic Arts" and the consequent abolition of all endowments for the studies of Sight Recognition, Mathematics, and Feeling. Soon, they began to insist that inasmuch as Colour, which was a second Nature, had destroyed the need of aristocratic distinctions, the Law should follow in the same path, and that henceforth all individuals and all classes should be recognized as absolutely equal and entitled to equal rights.

Pt. 2, ch. 20
Atticus Finch
To Kill a Mockingbird (1962)

Business Week Mindanao http://www.businessweekmindanao.com/category/businessdaily-headlines/page/20/
2013

Source: 2010s, 2016, July, 2016 Republican National Convention (21 July 2016)
Context: "I am the law-and-order candidate" was a phrase used by Richard Nixon during his 1968 presidential campaign.

Marriage protest (1855)

1960s, First court statement (1962)
Context: In its proper meaning equality before the law means the right to participate in the making of the laws by which one is governed, a constitution which guarantees democratic rights to all sections of the population, the right to approach the court for protection or relief in the case of the violation of rights guaranteed in the constitution, and the right to take part in the administration of justice as judges, magistrates, attorneys-general, law advisers and similar positions.
In the absence of these safeguards the phrase 'equality before the law', in so far as it is intended to apply to us, is meaningless and misleading. All the rights and privileges to which I have referred are monopolized by whites, and we enjoy none of them. The white man makes all the laws, he drags us before his courts and accuses us, and he sits in judgement over us.

Source: Utilitarianism (1861), Ch. 5