Law enforcement officers in New Jersey have breath analysis equipment to detect and measure alcohol intoxication. Detecting and measuring marijuana intoxication, however, poses multiple challenges. To prosecute cases against drivers allegedly influenced by marijuana generally requires evidence, but breath tests for marijuana so far cannot reasonably measure how much a person has used or when.
New Jersey and Massachusetts judges dismissed over 30,000 breath tests after it was discovered that human error, poorly maintained equipment and other issues made at least some of the tests inaccurate. Some devices reported blood alcohol content as much as 40% higher because of improper calibration.