There are two main ways of spelling and printing Latin:  academic and Ramist.  The “Ramist” form, which distinguishes semivocalic “J” from “I” and semivocalic “V” from “U,” is named after its early proponent, iconoclast French humanist logician and mathematician Pierre de la Ramée (1515-1572 [murdered]), Latinized as Petrus Ramus.  (The idea of such a distinction had been first suggested by the Spaniard Antonio de Nebrija in 1492 and again by the Italian Giovanni Trissino in 1529.)  The academic form is today used primarily by those in public schools, colleges and universities, while the Ramist form was used extensively everywhere in the seventeenth through nineteenth centuries, and until recently by the Roman Catholic Church.  After the Second Vatican Council (1962-65) and the complete elimination of Latin in many liturgical texts, the remaining Church Latin has tended to be written (often, alas, poorly and with many mistakes!) in the academic manner.

This is a pedantic mistake.

The academic form pretends to imitate the writing of the ancient Romans.  This is seen primarily in those semivowels which in English are written with the letters “W” and “Y.”  For both /W/ and /U/, the Romans used “V” representing them in stone or metal monuments, but “U” when writing on paper (papyrus) or wax.  (The change in pronunciation to the sound of the English (and French) consonant “V” for the semivowel came toward the end of the Empire.)  In its extreme form, the academics use the upper-case letter “V” for “U” when capitalized, and the lower-case letter “u” for “v” when not.  Thus, the Latin word for “vulnerable,” which is written in Ramist Latin respectively as “VULNERABILIS” or “vulnerabilis,” is found in many academic texts as “VVLNERABILIS” and “uulnerabilis.”  No orthographic distinction is made between them, and the academics pronounce the semivowel like English /W/, not /V/.  They pronounce the vowel like English /U/ (as in “rule”).

Most academic editors do not go so far.  But many are quite inconsistent:  they will print “VVLNERABILIS” in capitals, but “vulnerabilis” in lower case.

But virtually all academics omit the use of the letter “J.”  As mentioned, this letter, suggested originally by de Nebrija, was popularized by French professor Petrus Ramus around 1548 (in his Grammatica Latina) to designate the semivowel written in English as the letter “Y” (as in “you”).  In contrast, modern academics use only the letter “I” (and “i” in lower case).  Thus, the name for the first month of the year is written academically as “Ianuarius,” as opposed to Ramist “Januarius,” and the word for “justice” is written respectively as “iustitia” rather than as “justitia.”  (The Romans, by the way, placed no dot atop the lower-case “i.”  Thus in that way, too, even “iustitia” deviates from ancient writing practice.)  The name given to the new letter in Latin was jota (pronounced “yōta”) from the Greek (ἰῶτα or ïōta) for the letter “I.”  From this we get Spanish jota, German Jot, both meaning “the letter ‘J’,” and English “jot” as well as “iota.”

Following the suggestions of de Nebrija and Trissino, Petrus Ramus not only introduced “J”;  he also reserved “V” — the latter originally used only in monumental inscriptions — to serve as a letter corresponding to the semivowel spelled in English with “W.”  Today both letters occupy an important place in the English alphabet.  In Latin, the phonological reality underlying them is not negligible:  for instance, there is a clear difference between etiam (“also”) and et jam (“and already”), or between īēns (“going”) and jentāculum (“breakfast”).  Given the distinction, when “I” is used in transliterating words introduced from Greek such as ïambus (ἴαμβος “iamb,” a metrical, “short+long” foot in poetry), it is immediately evident that the initial letter does not represent a semivowel but a vowel;  Ramus’s innovation is also helpful in distinguishing between words such as the following:

or even between sequī (infinitive of sequor, “I follow”) with /kw/ (since u after q is always /w/, not /v/) and secuī (past tense of secō, “I cut”), with /ku/.  Another noteworthy case is the group of words beginning with su- as in suāvis “sweet,” suādeō “I persuade” and suēscō “I accustom,” in which the pronunciation is /sw-/, not /sv-/;  and there is also āiō “I say,” which is better written as ajo, i.e., ājō (or occasionally even as ājjō).

The academic practice is full of inconsistencies.  To begin with, among the great number of modern English words derived from Latin, we use j, not i:  we spell “conjecture,” not “coniecture” (Ramist Latin conjectura versus academic coniectura).  It makes it easier for students to learn Latin if we print j in the dictionaries and textbooks we use, since the j (and v) forms are already so familiar to them.  This fact alone means that, in learning to speak Latin (i.e., use it), rather than merely reading it, the Anglophone learner will have an easier time.

Next, the ancient Romans wrote in a way foreign to us today.  As Clive Brooks, an English scholar, points out in his Reading Latin Poetry Aloud (Cambridge, UK:  Cambridge University Press, 2007, p. 24):  “…with manuscripts written in capitals or uncials (rounded capitals), without punctuation and with no spaces between the words, even experienced readers must have needed to practice a bit” (Brooks’ italics).  Thus, if we want to write in true Roman style, let us compare the beginning lines of the Apostles’ Creed in Latin.  The English is

Next we can consider the “neo-Ramist” use of the digraphs Æ (æ) and Œ (œ), both of which are often pronounced in the Italian way as English “long A,” as in the word “rate.”  In Roman times, these were spelled separately as “AE” and “OE,” and were pronounced as dipthongs /ai/ and /oi/.  But in the Middle Ages they coalesced into monophthongs (single sounds), and their modern English descendants are also pronounced monophthongally, e.g., “preposition” from Latin “præposition-” and “economy” from Latin “œconomia” (originally Greek οἰκονομίᾱ).  The Ramist spelling and pronunciation are much closer to modern English practice, and hence easier for English speakers to learn.

Moreover, when we use the spelling “quum” for the conjunction  “(at the time) when” (with indicative) or “since, while, having [+ perf. part.]” (with subjunctive), and “cum” for the preposition “with” (which takes the ablative case), it is much easier to distinguish between these words than when both are spelled in the same way as “cum.”  Quum was originally a fossilized accusative of quī, as the Oxford Latin Dictionary (p. 468) notes, and says that it was “apparently usual before the Ciceronian period and thereafter in archaizing writers.”  So it has a solid grounding in ancient Roman practice.

An additional benefit of using “æ” and “œ” is that it is also easier to tell from sight alone when foreign words such as “Israel” (i.e., Isra-el) and “Michael” (Micha-el) are to be pronounced with the “A” separate from the “E,” since the two letters are themselves separate.  (Indeed, such names are in fact composites of separate words.)

Finally, from Allen and Greenough’s New Latin Grammar for Schools and Colleges, Founded on Comparative Grammar, Updated for Focus by Anne Mahoney (Newburyport, MA:  Focus Publishing, R. Pullins Co., 2001, p. 9, § 16):

Thus the Ramist form of spelling is the preferable way to write and learn Latin.  For modern students of the Latin language, it should be the first and main avenue for accessing the written records of that beautiful tongue.