One of several new laws that go into effect in Missouri on Tuesday is in honor of an Overland Park teenager kidnapped and murdered in 2007.
Missouri becomes the eighth state in the country to enact Kelsey's Law.
The law has been gaining ground steadily since 2009, when it went into effect in Kansas.
Three years later, it will be a Missouri law as well.
It's named after Kansas teenager Kelsey Smith whose body was found four days after she was abducted in southern Kansas City, Mo.
Since their daughter was murdered in 2007, Greg and Missy smith have toured the county telling their story.
In Smith's instance and others, officers said requesting location information from cell phone companies on people who are in danger took too much time.
Although federal law allows cell phone companies to provide location information to law enforcement in certain circumstances, Kelsey's Law seeks to mandate it.
And that means officers have less red tape to go though to get access to information that could save lives.
"If someone is missing and the police believe that they are in danger of physical harm or death, then they can ask the cell phone provider to locate that cell phone, where is it at," Greg Smith said. "That is the only information they get. They don't get content, they don't get to look to text messages."
The law is designed to be used during cases of immediate danger. It's not for routine investigations.
It allows wireless carriers to provide information to police and 911 dispatchers free of liability.