LAST WEEK, the Department of Homeland Security presented an outline for a major change in immigration enforcement and detention that has the potential to harm everyone, including U.S. citizens.

The new policies put most of the estimated 11 million undocumented immigrants in this country at risk for arrest and deportation, no matter how law-abiding or hard-working, no matter if they are parents of young children who are citizens or elderly infirm people who have been in this country-and paid taxes here - for decades.

The plan will triple the number of Immigration and Customs Enforcement agents to 15,000. It will also increase the number of detention centers. (The private prison industry is salivating over the new business). The main weapon in the feds' arsenal is heightened fear and suspicion and the potential for abuse of the Fourth and Fifth Amendments, which require "probable cause" for arrests and due process of law.

It's already started. Detailed warnings on Facebook and Twitter of immigration checkpoints in various cities spread like wildfire after immigration raids across the country resulted in 680 arrests a couple of weeks ago. The rumors were false, but the panic was real, aggravated by reports of arbitrary and inhumane arrests. Officials have warned against scam artists posing as ICE agents seeking to extort money from people who are afraid for themselves or family members.

Children already are being kept out of school. Colleges are bracing for immigration raids, and trying to reassure students that the institutions won't cooperate. Some immigrants are seeking sanctuary in churches.

This is not what most of us want. In a recent CBS poll, 73 percent of respondents said they did not want undocumented people to be deported, with 60 percent supporting a path to citizenship. At this point, though, what the American people want doesn't matter. The president has wide powers over immigration and he continues to slander immigrants as "bad, bad people." As he said last week, "Get them the hell out of here. Bring them back to where they came from."

But Philadelphia remains a "Fourth Amendment City," a more apt description of policy than "Sanctuary City." In the absence of warrants, local law enforcement won't cooperate with federal immigration officials to detain undocumented immigrants who are in custody for nonviolent crimes. In a conflict between ICE and the Constitution, we choose the Constitution.

Some Philadelphians are organizing to take action. Last Friday, 200 people, mostly lawyers, jammed into the Loews Hotel to learn how they can provide pro bono legal aid to immigrants and refugees, a gathering sponsored by the City and the Philadelphia Bar Association. (Lawyers who want to volunteer can find more information at #TakeActionPhilly.) In addition, about 1,300 people have signed up with nonprofit New Sanctuary Movement to be trained in how to respond nonviolently to ICE arrests, including peacefully disrupting them.

What you can do: The Pennsylvania Senate has passed a bill that would deny funds to "sanctuary cities," including many more beyond Philadelphia. The Indivisible organization urges you to call friends or relatives in other districts and ask them to contact their representatives in the Pennsylvania House to oppose the bill. For more information, check the Indivisible/Northwest Philly's Facebook page.