The Denver Police Department is looking for funding to install 20 high-tech surveillance cameras downtown before August’s Democratic Convention. The cameras will be able to “capture images as detailed as faces and license plates, said police Sgt. Ernie Martinez.” Civil liberties advocates object, saying the cameras will discourage lawful protest.

“There is no need to spy. This is spying,” said Cathryn Hazouri, executive director of the American Civil Liberties Union of Colorado. “You could be chilling the free expression of political dissent. People may be less likely to express themselves because of the fear of being on tape by the police.”

The cameras aren’t just for the convention. The DPD will keep them in place long after the convention is over. Nor are they cheap:

The cameras can cost $20,000 for a permanent hard-wired video unit or $10,000 to $12,000 for a network of three or four wireless cameras that can be moved.