MINEOLA, N.Y. - As synthetic drugs become more popular, prosecutors in New York and a dozen other states are finding themselves stymied by a law that allows them to charge drivers with drugged-driving only if they're under the influence of something on an official list of banned substances.

Prosecutors say the problem is that synthetic drug manufacturers are changing the composition of their drugs before the law can catch up.

Legislation is pending in New York seeking to change that law to fall in line with the dozens of other states that allow for such charges based on police observations of the impairment of the driver.

In addition to New York, such banned-list laws exist in Minnesota, Arkansas, Ohio and nine other states.