The American Civil Liberties Union of Pennsylvania has filed a federal lawsuit on behalf of a U.S. citizen who was detained for three days because authorities believed he was in the country illegally from the Dominican Republic.

The ACLU said Ernesto Galarza, a New Jersey-born U.S. citizen of Puerto Rican descent, was mistakenly arrested by Allentown police during a roundup of drug suspects in November 2008.

Galarza, 36, posted bail the next day, but was then detained by the U.S. Immigration and Customs Enforcement, which was investigating whether he could be deported to the Dominican Republic.

?This kind of injustice is what happens when law enforcement engages in racial and ethnic profiling,? said Valerie Burch, a staff attorney with the ACLU of Pennsylvania and one of the attorneys representing Galarza.

The ACLU said Galarza?s Social Security card and Pennsylvania driver?s license were in his wallet at the time of his arrest and in the prison?s possession during his detention.

?I was shocked and upset that they assumed I am an immigrant," said Galarza. "No one bothered to check or ask me about it. It?s clear that they only reason they decided I?m Dominican is because I?m Latino. I was born in New Jersey, and I?m a proud American. This isn?t how Americans should be treated. It?s like getting slapped in the face.?

Galarza was later acquitted of any criminal wrongdoing.

The ACLU said the Allentown Police Department has a policy of aggressively enforcing immigration law and works closely with ICE to identify immigrants thought to be in the United States illegally.

?This case is a perfect example of how ?aggressive? enforcement of immigration laws in the supposed name of keeping us safe from immigrant criminals can lead to devastating consequences for law-abiding Americans,? said Jonathan H. Feinberg of Kairys, Rudovsky, Messing & Feinberg LLP, another attorney representing Galarza .

In its lawsuit, the ACLU accuses ICE, the Lehigh County Prison, and the Allentown Police Department of collaborating to violate Galarza's civil rights.

The lawsuit seeks damages for Galarza, who the ACLU said lost a part-time job and wages as a result of his imprisonment.

ICE has declined to comment about the case. Allentown officials said they're reviewing the lawsuit.