Source: Tests indicated Bieber's BAC was .011%, .014%
Both would be below .02% limit for drivers under legal drinking age of 21
Test checks only for alcohol; DUI law also prohibits impairment by controlled substances
Chief: Bieber said he drank, smoked pot, took prescription medication before driving Thursday
Two breath tests estimated pop star Justin Bieber’s blood-alcohol content was below .08% after his arrest on suspicion of driving under the influence in Florida, a source close to the investigation said Friday.