HIPAA law and implementing regs include broad allowances for disclosure to law enforcement, some of which involve some degree of subjective judgement on the part of the covered entity (and most of which do not require a warrant), but, no, it does not allow pharmacies (or any other covered entities) "leeway as to what legal standard they require" (emphasis added) before such disclosure.

See, generally, https://www.hhs.gov/hipaa/for-professionals/faq/505/what-doe... and the regulations cited therein.