Wikipedia has an article on the number 19, which includes mathematical info like "19 is the aliquot sum of two odd discrete semiprimes, 65 and 77 and is the base of the 19-aliquot tree." And "19 is a centered triangular number, centered hexagonal number and a Heegner number" — which looks like this:
That red dot could be John Roberts.
There's also significance to the number 19 in the religions Islam and Baha'i:
The number of angels guarding Hell ("Hellfire") according to the Qur'an: "Over it is nineteen" (74:30).Not at the Wikipedia, but dredged up out of my memory: At the Million Man March, back in 1995, when Louis Farrakhan gave his long speech that bizarrely drifted into numerology, the number that he found so important was 19. He observed that the Jefferson and Lincoln Memorial are both 19 feet high, then adds 3 and 16 together — because Thomas Jefferson was the 3d President and Lincoln was the 16th — gets 19 and asked "What is so deep about this number 19?" You can go to the link and read if you want to know why 19 represents a pregnant woman + a "secret that has to be unfolded."
The Number of Verse and Sura together in the Qur'an which announces Jesus son of Maryam's (Mary's) birth (Qur'an 19:19).
Some people have claimed that patterns of the number 19 are present an unusual number of times in the Qur'an.
In the Bábí and Bahá'í faiths, a group of 19 is called a Váhid, a Unity (Arabic: واحد wāhid, "one"). The numerical value of this word in the Abjad numeral system is 19.
The Bahá'í calendar is structured such that a year contains 19 months of 19 days each (along with the intercalary period of Ayyám-i-Há), as well as a 19-year cycle and a 361-year (19x19) supercycle.
The Báb and his disciples formed a group of 19.
There were 19 Apostles of Bahá'u'lláh.
I don't know what put the idea of 19 into Jonathan Turley's head. It could be something mystical and nutty. Maybe he loves Adele's first album.
But I assume there's nothing mystical or artistic about Turley. I think he likes the number 19 because it's the smallest odd number that's big enough to make individual Justices inconsequential — to dilute their power to the point where they don't loom large as personalities and seem like mere humans.
Turley's last sentence says it: With 19 Justices, "the power of individual judges is diluted."