The falling sky clause occurs in the passage of Terence, suggesting that it was a common saying in his time, “Quid si redeo ad illos qui aiunt, ‘Quid si nunc cœlum ruat?’” — “What if I have recourse to those who say, ‘What now if the sky were to fall?’”
This concern recalls a passage in Arrian’s Campaigns of Alexander, Book I, 4, where ambassadors of the Celtae from the Adriatic sea, tall men of haughty demeanor, upon being asked by Alexander what in the world they feared most, answered that their worst fear was that the sky might fall on their heads. Alexander, who hoped to hear himself named, was disappointed by an answer that implied that nothing within human power could hurt them, short of a total destruction of nature.
In a similar vein, Theognis of Megara urges “May the great broad sky of bronze fall on my head / (That fear of earth-born men) if I am not / A friend to those who love me, and a pain / And irritation to my enemies.” Whereas Aristotle asserts in his Physics, B. IV, that it was the early notion of ignorant nations that the sky was supported on the shoulders of Atlas, and that when he let go of it, it would fall.
On the other hand, Horace opens one of his odes with a depiction of a Stoic hero who will submit to the ruin of the universe around him: "Si fractus illabatur orbis, / impavidum ferient ruinae" — "Should the whole frame of Nature round him break, / In ruin and confusion hurled, / He, unconcerned, would hear the mighty crack, / And stand secure amidst a falling world." (Odes 3.3.7-8, translated by Joseph Addison.)
In subsequent retellings of this legend, this principle became known as “Piso’s justice”, which is when sentences made or carried out of retaliation intentions are technically correct, but morally wrong, as could be a negative interpretation of the meaning for Fiat justitita ruat caelum.
However, no form of the phrase fiat justitia appears in De Ira, though Brewer's incorrectly states that it does. The phrase is sometimes attributed to a different Piso, Lucius Calpurnius Piso Caesoninus, possibly a confusion with this case.
The exact phrase as used for approval of justice at all cost – usually seen in a positive sense – appears to originate in modern jurisprudence. In English law, William Watson in “Ten Quodlibetical Quotations Concerning Religion and State” (1601) “You go against that general maxim in the laws, which is ‘Fiat justitia et ruant coeli.’” As is known, this is its first appearance in English literature.
The maxim was used by William Prynne in “Fresh Discovery of Prodigious Wandering New-Blazing Stars” (1646), by Nathaniel Ward in “Simple Cobbler of Agawam” (1647), and frequently thereafter, but it was given its widest celebrity by William Murray, 1st Baron Mansfield's decision in 1772 on the James Somersett case that led to abolition of slavery in England.
The maxim is given in various forms:
A famous use is by Immanuel Kant, in his 1795 Perpetual Peace (Zum ewigen Frieden), in the form Fiat justitia, pereat mundus, which he translates loosely as "Let justice reign even if all the rascals in the world should perish from it".
More recently, Judge James Edwin Horton referred to the maxim when he recalled his decision to overturn the conviction of Haywood Patterson in the infamous Scottsboro Boys trial. In 1933, Judge Horton set aside the death sentence of Haywood Patterson, one of nine black men who were wrongfully convicted of raping two white women in Alabama. Judge Horton quoted the phrase when explaining why he made his decision, even though he knew it would mean the end of his judicial career.
Similarly, Lord Mansfield, in the June 1772 Somersett decision that abolished slavery in England, used Lucius Calpurnius Piso Caesonius's phrase to reflect upon the duty of the Court.
The phrase is engraved on the wall behind the bench in the Supreme Court of Georgia and over the lintel of the Bridewell Garda station in Dublin. "Fiat Justitia" appears at the bottom of the portrait of the Great Chief Justice John Marshall by Rembrandt Peale. Peale's 1835 portrait of Marshall hangs in a conference room at the United States Supreme Court.
This is also the motto of the United Kingdom Royal Air Force Police and it is displayed on the RAF Police Crest.
The phrase "Fiat Justitia" appears in gray block letters as an epitaph to Chief Justice John Marshall in Rembrandt Peale's 1835 portrait of the Great Chief Justice of the United States. The portrait hangs in the East Conference Room of the United States Supreme Court.