Better watch what you say next time you take the bus; somebody could be listening in.

We’re all pretty used to the increasing amount of cameras on public transportation, and a lot can be said in their favor. They provide a safer environment for the driver when dealing with unruly passengers. They allow law enforcement to capture images of people they’re trying to identify. They can even help in returning a lost child to parents or at least tracking their whereabouts.  In general, most people don’t even notice them, let alone bother worrying about what they’re recording.  Let’s face it: Being on surveillance is part of living and participating in public society.

But at what point does the slippery slope of privacy invasion take a step too far? In general, people are indifferent—or at least resigned—to a video recording, but what happens when the government starts recording conversations?

Well, stay tuned, because that’s happening in San Francisco, Baltimore and a few other cities around the country, according to The Daily.

Apparently, the paper discovered that a few city governments have decided to sync audio with the ever-present security cameras already installed. This will allow the government to basically transcribe any conversation you’re having on the bus, match it up with your face, and store it for up to 30 days.

According to The Daily, the contract specifies the audio systems will be installed in 357 modern busses and historical trolley cars over four years.

The technology is pretty advanced as far as mass implementation of audio recording devices goes. Some companies are promising a signal-to-noise ratio greater than 48 decibals, not to mention audio that records over engine noise, rain, snow, loud voices, and the general mayhem of a bus.

The legality of the situation seems to be a bit hazy. According to claims filed in Connecticut, civil liberties groups are concerned the audio is crossing the line into illegal wiretapping, while law enforcement agencies—and bus companies—claim it will allow them to better solve crimes and settle customer complaints.

They’re basically equating this to having a police officer on every bus just sitting there listening, but it’s really quite different. You don’t have the proactive presence of the police to dispel violence or issues while they happen, you simply have to wait and play back the tape. Even if it’s recorded in real time, the police office won’t be physically present, so it will be a lot – literal – he said, she said.