"statement in passing," a judge's expression of opinion not regarded as binding or decisive, Latin, literally "something said incidentally;" from obiter "by the way" + dictum in the legal sense "a judge's expression of opinion which is not the formal resolution of a case or determination of the court."
Obiter dicta, legal dicta ... uttered by the way (
obiter), not upon the point or question pending, as if turning aside for the time from the main topic of the case to collateral subjects. [Century Dictionary]
Latin obiter is from ob "in front of, toward" (see ob-) + iter "journey" (from PIE root *ei- "to go"). Klein's sources, however, say it is ob with the suffix -iter on analogy of circiter "about" from circa. Also see obituary.