We showed iPhone user Moniqua Griffin how to find her list.
She said, "For you to just be able to look it up like that, that ain't good."
It can be good for your boss, for example, if you have a work phone and he wants to know if you were really sick when you called out one day.
"I think that's a complete invasion of privacy," said Katz, who admitted he could also see some benefit to the technology.
"That's good for checking up on your girlfriend too!" he joked. His girlfriend who was standing right next to him replied, "No, that's horrible!"
If someone thought a spouse was cheating, the truth could be right there in their phone.
"Wow, that is awesome," exclaimed Clayton County District Attorney Tracy Graham Lawson when she saw the technology for the first time.
"It's scary from a Big Brother point of view, but it's awesome for law enforcement purposes," she added.
Lawson says prosecutors have used cell tower data for years. But now, if a suspect swears he wasn't at the house that got robbed, his phone could say he was and at the exact time of the crime.
"It's by far better, otherwise they're pinging a general location. This gives the exact address, this is awesome for us," Lawson said.
"If they go through the proper warrant procedures it's perfectly appropriate for them to get this information," sad Atlanta attorney Gerry Weber, who specializes in constitutional law.
Weber admits he finds the new technology a little scary.
"Anybody could grab your cellphone and see where you've been over the last several months, date and time and place. I don't think anybody would imagine that," said Weber.
He worries the accessibility of the information might be too tempting for officers to wait for a search warrant.
"The officer might grab the phone, look and see where you've been, and use that information, and not ever tell anybody that they got it from your phone," said Weber.
He wonders if Apple might eventually do the same, and share or sell locations for marketing.
According to Apple's website, “Your iPhone will keep track of places you have recently been, as well as how often and when you visited them, in order to learn places that are significant to you. This data is kept solely on your device and won't be sent to Apple without your consent. It will be used to provide you with personalized services, such as predictive traffic routing.”
You automatically consent when you allow Apple to “use your frequent locations” to improve your maps feature.
Apple refused to disclose how often your phone records your location, and whether it's triggered by a specific act like a call or a text.
"There's so much information out there. It's so rich. It's so revealing. They all want their hands on it," said Hanni Fakhoury with the Electronic Frontier Foundation, a San Francisco based non-profit that defends privacy rights.
Fakhoury questions why Apple automatically activates the frequent locations feature when users agree to basic location services.
"When you are opted into the system automatically without any choice that's where there are some real problems," said Fakhoury.
Most of the smartphone users Channel 2 shared the feature with immediately asked how to disable it.