By RICK M. GREEN Capitol Bureau rmgreen@oklahoman.comA summit will be held Tuesday at the state Capitol to examine drug-impaired driving, including how the opioid epidemic and marijuana legalization have contributed to the problem. Breath and blood tests provide good standards for measuring alcohol in a driver's system, but it is harder to determine how other substances are affecting a driver. “When these folks get behind the wheel, it can be difficult for law enforcement to recognize the level of impairment,” said Chuck Mai, a spokesman for AAA Oklahoma, which is sponsoring the meeting. “Determining alcohol impairment is like kindergarten.Read more on NewsOK.com