Are drug dog alerts reliable?

An alert is treated as capable of establishing probable cause, but the reliability of a particular dog is contestable rather than assumed.

What gets examined: the dog's training and certification records, its performance history including false alerts, the handler's training, whether the handler may have cued the alert consciously or otherwise, and whether the alert was actually documented or only described afterward.

Those records exist and can be obtained. Performance histories are sometimes considerably less impressive than testimony implies.

There's a Florida-specific issue on top of that. A dog trained to alert on cannabis generally cannot distinguish legal hemp from illegal marijuana. One appellate court has noted that an alert adds little where the dog can't tell a lawful substance from an unlawful one. That argument's strength depends on the district, but the underlying point is sound.