The doctrine is subject to four main exceptions. The tainted evidence is admissible if:
it was discovered in part as a result of an independent, untainted source; or
it would inevitably have been discovered despite the tainted source; or
the chain of causation between the illegal action and the tainted evidence is too attenuated; or
the search warrant was not found to be valid based on probable cause, but was executed by government agents in good faith (called the good-faith exception).