Cops might as well wear blindfolds if the City Council passes a bill that would let them use little more than the color of a suspect’s clothing in descriptions — or risk being sued for profiling, according to this provocative new ad (pictured) from the NYPD captains union.

The ad asks, “How effective is a police officer with a blindfold on?”

And the answer is not very, says the NYPD Captains Endowment Association, which is fighting the measure, claiming it would handcuff cops and send crime rates soaring.

Union President Roy Richter — who is seen in the ad wearing a blindfold in Times Square — told The Post the bill is dangerous because “it will ban cops from identifying a suspect’s age, gender, color or disability.

“When we have wanted suspects and patterns of crimes, those are very important descriptive terms to let officers know who to look for.”

The ad warns that if cops transmit a description of a suspect that goes beyond the color of his or her clothing, they could be sued for racial profiling if the proposal becomes law.

The ad will appear in tomorrow’s Post, in addition to the union’s Web site, Twitter and Facebook — and provides links to contacts for City Council members to sway their vote on the measure.

The bill’s sponsor, Jumaane Williams (D-Brooklyn), and Speaker Christine Quinn are going to bypass normal committee process and bring the measure directly to a vote.

Detectives-union President Michael Palladino blasted Quinn for supporting the rare expedited process — and said his union plans to place ads in newspapers next week.

“The [union’s] ad will focus on . . . Speaker Quinn’s political decision to sell the security of all New Yorkers for votes. Where was the speaker and her legislation for the last seven years?” Palladino asked.

A rep for Quinn said she sent the proposals to a floor vote because a majority of council members supported it and Public Safety Committee chair Peter Vallone Jr. — an opponent — refused to let it out of committee.

PBA President Pat Lynch said the “so-called biased policing” package was a misnomer.

“Rather than focus on unnecessary laws, the council should be supporting its police officers — not attacking them,” he said.

“Racial profiling is already illegal — and should be.”

Williams and fellow Brooklyn Democrat Brad Lander, a co-sponsor of the proposal, say it would only expand the city’s existing racial-profiling law by adding other demographic groups that should be protected, such as the homeless and gay people.

They have said police are free, under the bill, to chase leads that include descriptions but cannot stop and frisk people based solely on those descriptions.

But the Bloomberg administration has warned that the bill could lead to an avalanche of lawsuits against the city by any members of a protected class who believe that they were profiled.

Additional reporting by Bob Fredericks