but cf.

But cf. is a citation signal used to cite an authority that supports an analogous but generally contrary proposition to the one advanced by the author. Using the signal but cf. invites the reader to consider reasoning from a similar factual or legal context that leads to an opposite or conflicting conclusion. Among citation signals, but cf. is the weakest of the negative signals and functions as the inverse of cf. (“compare”). While cf. introduces authority offering analogous reasoning in support of the author’s point, but cf. introduces authority offering analogous reasoning in opposition.

Example: “Even if the rule of res judicata were applicable in habeas corpus proceedings, but cf. Waley v. Johnston, 316 U.S. 101, 105 (1942), it would have no bearing in the present case.” Here, the citation to Waley v. Johnston provides an analogous but opposing analysis concerning the application of res judicata in habeas corpus proceedings.