Businesses and the government have spent years installing millions of surveillance cameras across the United States. Now, that technology is on the verge of getting a major upgrade, the American Civil Liberties Union warns in a new report.

Advancements in artificial intelligence could supercharge surveillance, allowing camera owners to identify “unusual” behavior, recognize actions like hugging or kissing, easily seek out embarrassing footage and estimate a person’s age or, possibly, even their disposition , the group argues.

“We face the prospect of an army of A.I. security guards being placed behind those lenses that are actually, in a meaningful way, monitoring us, making decisions about us, scrutinizing us,” said Jay Stanley, senior policy analyst at the A.C.L.U. and the author of the report, which was released on Thursday.

The United States is, by various estimates, home to tens of millions of surveillance cameras. While many of those devices have been around for years, it has been widely understood that it would be unfeasible, if not impossible, for each device to be constantly monitored and its footage carefully categorized and documented, Mr. Stanley notes in the report, titled “The Dawn of Robot Surveillance.” Even the Justice Department has said that watching such footage is “boring and mesmerizing,” and that attention fades after about 20 minutes.