Thought you only had to worry about the growing American surveillance state from the likes of the National Security Agency? Think again.

The Des Moines Register reported on Sunday that there are signs that over the past two years, Iowa law-enforcement agencies have been collecting data via “tower dumps.”

Tower dumps involve police departments requesting all records on call, text, and data sent through local cell towers over a given period of time, usually about when a certain crime occurred.

Whenever a mobile phone user is checking her or his email, using social media, or communicating with another person, that device is sending and receiving signals to and from the nearest cell tower.

Although the state of Iowa’s official policy requires obtaining a warrant before requesting troves of data through tower dumps, that doesn’t mean local police departments have to. According to an article in the University of Pennsylvania Journal of Constitutional Law, these tower dumps reveal an enormous amount of information and can simply be obtained through a subpoena.

“Subscriber or customer information also available based on a law-enforcement request may include the person’s name; address; telephone call records, including times and durations; lengths and types of services; subscriber number or identity; means and source of payment, including bank-account number or credit-card number; date of birth; Social Security number; and driver’s license number.”

As if that isn’t bad enough, there seems to be absolutely no transparency in the entire espionage operation against Iowans.

The Register reported that Iowa Department of Public Safety refused to say which police departments it assisted in analyzing cell data and how many tower dumps have occurred. The Department of Administrative Services also (as of Sunday) refused an open-records request for documents with information on payments that the Iowa Department of Public Safety made to a company that produces cell-tower simulators, devices that can intercept signals sent between mobile phones and towers.

Iowa’s law-enforcement officials seem to want the public to simply trust them. And that would be lovely if they all had hearts of gold, but there are too many instances in which the police have abused their power for us to reasonably trust that Iowa’s law-enforcement officials will always do the right thing when handling sensitive personal information.

After all, it was the law-enforcement community that brought the United States such scandals as the Counter Intelligence Program (better known as COINTELPRO), in which the FBI infiltrated and sabotaged political organizations during the 1970s. More recently, law-enforcement agencies have employed agents to infiltrate mosques and spy on the Occupy Movement. There have been numerous complaints of border agents using excessive force near the U.S.-Mexico border, including detention for no apparent reason along with illegally searching and confiscating private property.

Not surprisingly, the National Security Agency has also been involved in some shifty activities. An internal audit of the agency detailed 2,776 instances in which the NSA violated court orders for surveillance that occurred from April 2011 to March 2012.

We don’t think every single person or even most individuals in the law-enforcement community are “bad people.” However, the historical record, both looking well into the past through today, shows that when entrusting a small group of people with substantial power, some will abuse their authority. That is why transparency is non-negotiable, especially when dealing with something as precious as civil liberties.