Wikipedia
Dubitante (Latin: "doubting") is used in law reports of a judge who is doubtful about a legal proposition but hesitates to declare it wrong. E.g., "Justice X acquiesces in the Court's opinion and judgment dubitante on the question of Constitutional preemption."
Some judges use this term after their names in separate opinions, as if analogous to concurring or dissenting. Doing so may signal that the judge has doubts about the soundness of the majority opinion, but not so grave as to cause him to dissent. The legal philosopher Lon L. Fuller said that "the opinion entered dubitante [means that] the judge is unhappy about some aspect of the decision rendered, but cannot quite bring himself to record an open dissent."
Another use—doubt but lack of conviction that the majority is wrong—is illustrated in Judge Friendly's concurrence in Feldman v. Allegheny Airlines, Inc., in which he stated, "Although intuition tells me that the Supreme Court of Connecticut would not sustain the award made here, I cannot prove it. I therefore go along with the majority, although with the gravest doubts."
In 2005, Westlaw recorded 626 uses of the term in the United States. Nearly half of the instances of use of the term come from four federal court of appeals judges: Frank Coffin (First Circuit); Henry J. Friendly (Second Circuit); Frank Easterbrook (Seventh Circuit); and James C. Hill (Eleventh Circuit).