The American Civil Liberties Union has filed a lawsuit in Puerto Rico over new security measures being taken this year at a popular street festival in the island's capital that draws hundreds of thousands of locals and tourist.

Wednesday's lawsuit comes a day before the San Sebastian festival begins in historic Old San Juan. The celebration lasts four days and features music, art and food.

Mayor Carmen Yulin has ordered police for the first to search everyone who attends. Officials say that there will be metal detectors and that people's bags and purses will be searched.

The ACLU calls the searches unreasonable because they are not preceded by a judicial order or prompted by probable cause.

An estimated 500,000 people attended the festival last year.