A person who is charged with a DUI in Massachusetts may have difficulty contesting the matter in court if the chemical tests reveal that the blood alcohol content is above the legal limit of 0.08 percent. Drugs may also affect driving skills, but as NBC Boston notes, proof of the impairment may not be as easy to come by for law enforcement officers attempting to make an arrest. In addition, many authorities are untrained in positively identifying whether a driver is high.

Even so, officers issued more than 1,500 citations for operating under the influence of drugs during 2015. These include cases involving marijuana, opioids, prescription drugs and other substances. Recently proposed legislation recommends setting a legal limit for marijuana use, but currently, there is no defined threshold for this or any other drug.

Some believe the pace of legislation cannot keep up with the steady increase of motorists who are driving while impaired, according to NBC Boston. A federal program now supplies state law enforcement with the opportunity to try out a chemical test that would indicate whether there are drugs in a driver’s system. A machine is calibrated to detect drugs such as methamphetamines or marijuana on a cotton swab, which the officer collects when a person is suspected of driving under the influence. To ensure that the machine’s results are correct, a second swab is sent to an independent laboratory.

Throughout the course of the trial phase, which will remain in effect for several months, officers can only administer the test if a person agrees voluntarily to take it.