Teen who falsely accused ex-boyfriend of drugging and raping her when they split up is convicted of wasting police time
I don’t think it’s a legal definition as opposed to a law enforcement classification. Based on a rough read of the literature, you seem to get three basic categories:
False = evidence that no crime was committed. That is, an affirmative demonstration of innocence following an investigation. The example in the OP was a “false” allegation (the body camera evidence was persuasive evidence that the facts alleged did not occur).
Baseless is somewhat slippery because it seems to include situations where the facts alleged are insufficient as a legal matter to demonstrate a crime as well as a person is not able to allege sufficient facts to make a crime (for example, someone who drunk and is uncertain whether or not they were assaulted).
Unsubstantiated = unable to prove that a crime occurred (typically after an investigation), this is likely going to include insufficient corroborating evidence, an uncooperative victim, and other investigative issues.
I see, at least, two problems with using “false or baseless” as the criteria of “false” accusations. First, baseless isn’t really like false (there’s no allegation of dishonesty). Second, I think that two things are true: (1) most “unsubstantiated” allegations are, in fact, “true” (even if not provable) and (2) most “fake” allegations will be determined to be “unsubstantiated” not “false” (most people don’t have body cameras).
Similar case here - false accusations for personal gain/profit.