Salus populi suprema lex esto (Latin: "The health (welfare, good, salvation, felicity) of the people should be the supreme law", "Let the good (or safety) of the people be the supreme (or highest) law", or "The welfare of the people shall be the supreme law") is a maxim or principle found in Cicero's "De Legibus" (book III, part III, sub. VIII).
There are no less than 3 books that comprise Cicero's "De Legibus"
The context mentions that the law is in Book 3 of Cicero's "De Legibus." So there are at least 3 books that comprise the work. The computer was likely fooled because the context uses roman numerals to denote 3.