The legal example is actually maybe even more interesting than you may think. The big traditional databases have always employed human reviewers to identify cases that overrule or question other cases. Attempts to automate this process by e.g. Casetext have had somewhat limited success, despite the fact that this is a restricted context with formal language. It’s getting better, but whether it will ever be good enough is still an open question.
(By the way, signals are not much used in opinion writing; that aspect of the Bluebook is geared more towards law reviews. Approval or disapproval of prior authority is in the opinion text itself, as this is a formal activity of the court. Notation as to whether a given cited case approves or disapproves another case would be in a parenthetical after the citation, e.g. “Smith v. Jones 123 Foo2d 456 (1999) (overruling Jones v. Smith 12 Foo2d 345 (1989)).”)
See https://en.m.wikipedia.org/wiki/Shepard%27s_Citations
(By the way, signals are not much used in opinion writing; that aspect of the Bluebook is geared more towards law reviews. Approval or disapproval of prior authority is in the opinion text itself, as this is a formal activity of the court. Notation as to whether a given cited case approves or disapproves another case would be in a parenthetical after the citation, e.g. “Smith v. Jones 123 Foo2d 456 (1999) (overruling Jones v. Smith 12 Foo2d 345 (1989)).”)