Christos Sourovelis already considered May 8 - the day he dropped his son off for a stint in court-ordered rehab - as one of the worst in his life. Then, it got worse.

That afternoon, more than a month after police arrested their son for selling $40 worth of drugs outside of their house in the city's Somerton section, Sourovelis received a frantic call from his wife. Officers had returned, and this time they were looking to take their home.

So began his family's introduction to the city's civil forfeiture dragnet - a program ostensibly aimed at depriving drug traffickers of cash, cars and other fruits of their crimes but one increasingly under a microscope for cases like Sourovelis', in which homeowners never accused of anything still face eviction from houses only tangentially related to a crime.

"I didn't do anything wrong. I didn't bother anybody," Sourovelis, 52, said in an interview Tuesday. "But we struggle from week to week not knowing what will happen."

This week, he and two other Philadelphia homeowners whose houses have become targets of civil forfeiture actions sued the District Attorney's Office, the city and the Police Department, seeking to close down what their lawyers call one of the most aggressive forfeiture units in the nation.

"The Philadelphia District Attorney's Office has turned this tool into a veritable machine, devouring real and personal property from thousands of residents, many of whom are innocent, and converting that property into a $5.8 million average annual stream of revenue," said Darpana Sheth, a lawyer with the Virginia-based Institute for Justice, a nonprofit public-interest law firm with libertarian leanings.

The lawsuit, filed Monday in a federal court in Philadelphia, alleges that the city's Public Nuisance Task Force makes millions each year in a Kafkaesque system designed to grind down or trick often innocent property owners until they give in or make procedural missteps that can result in the loss of their property.

The plaintiffs seek only a nominal $6 in damages each, but have asked a judge to shut down the city's civil forfeiture program on constitutional grounds. Their lawyers are seeking class-action status for the case.

Tasha Jamerson, a spokeswoman for District Attorney Seth Williams, defended the city's forfeiture program in a statement Tuesday, calling it an important tool in the fight against drug trafficking. The targeted homes, she said, are often "rife with drug use, drug dealing and violence."

"Even more tragically, these activities invariably spill out into the streets and neighborhoods surrounding the property," she said.

State lawmakers authorized the process of civil forfeiture in 1988. Proceeds from seized properties are funneled back to local prosecutors and police. And unlike criminal cases, which must be proven "beyond a reasonable doubt," the civil route offers prosecutors many advantages.

Chief among them, government lawyers must prove only that a property - not its owner - was "more likely than not" involved in the perpetration of a crime.

The state's civil forfeiture laws also allow prosecutors to go after properties suspected as criminal hotspots even if no one associated with them is ever charged with a crime. Judges can sign off on seizure orders before the adjudication of a criminal case.

That can lead to situations in which a judge approves a civil forfeiture of a house, only to find later that a jury has acquitted the property owner of the crime that led to its seizure in the first place, said Louis Rulli, a University of Pennsylvania Law School professor and nationally recognized expert on civil forfeiture.

"What we have is a law that was intended to go after drug kingpins and take away the tools of the trade, and instead we see it used against innocent folks, most of modest means," he said. "I don't think that sits well with the American public."

Whatever the merits of civil forfeiture, the sheer volume of cases Philadelphia has pursued is remarkable.

Across Pennsylvania, Philadelphia is a clear leader in the forfeiture front, accounting for nearly half of all money and property seized across the state between 2002 and 2012. Per capita, the city has seized nearly $43 per resident during the same period - more than twice that of the next most active county.

Philadelphia has brought in more than $64 million in seized property during the last decade - almost twice the amount raised by similar programs in Brooklyn, N.Y., and Los Angeles County combined.

Proceeds make up almost 20 percent of the annual budget of the District Attorney's Office. Forty percent pays for prosecutor salaries, including those of the lawyers involved in forfeiture proceedings. Critics say those numbers create a clear profit motive for city prosecutors to pursue forfeiture actions at all costs.

"There is no question that Philadelphia has an aggressive civil forfeiture program that is used much more than anywhere else in the state," Rulli said.

Sourovelis' case, his lawyers said Tuesday, demonstrates that those seizures don't always target the drug dealers the law was intended to hurt.

Though his son was charged in March, no evidence was ever uncovered that the parents had any knowledge of his alleged drug-dealing.

In the meantime, however, the Sourovelis family was kicked out of their house for a week after the seizure order. They have since been allowed back in - on the condition that their son live elsewhere. But their future is by no means certain.

Every month, Sourovelis said, the couple must return to Room 478, the City Hall courtroom where all forfeiture cases are heard, in hopes of finally pleading their case before a judge. Time and again, he said, no judge is present and their case is put off.

"We tried to explain all this to the officers when they first took our home, and they told us to tell our story to the judge," Markela Sourovelis said. "In three months, we have yet to see a judge."

David Rudovsky, local counsel for the plaintiffs, said the Sourovelis' experience is not uncommon.

Property owners facing forfeiture are summoned to City Hall, where they are initially ushered into a room with no judges and no juries. Prosecutors alone are on hand to dispense legal advice, Rudovsky said, and more often than not, they inform homeowners under threat that their cases are simple and they do not need a lawyer to represent them.

Cases are often reset dozens of times before making their way before a judge - part of a practice to drag out forfeiture efforts until associated criminal prosecutions are adjudicated, the lawyer said in court filings.

That leaves homeowners such as Norys Hernandez, one of the plaintiffs in the suit filed this week, on the hook for months. Police seized the South Philadelphia rowhouse she and her sister owned after her nephew was arrested in April on drug-dealing charges.

"My sister was away in Puerto Rico at the time," Hernandez said Tuesday. "She didn't even have a chance to grab any of her things before they seized the property. She still isn't allowed to go back."

An Institute for Justice review of more 8,000 forfeiture cases in the city found that property owners must return to court five times on average before their cases are resolved. Miss one hearing, said Rudovsky, and the property is forfeited.

"If they can't tolerate going to court 10 times to resolve this - as many people can't, with work and other commitments - they lose out," the lawyer said.

Jamerson, the district attorney's spokeswoman, said that "in all efforts, we follow applicable law to protect the rights of all of those involved - not only drug dealers . . . but the law-abiding citizens who are negatively affected by them."

A hearing date in Sourovelis' suit against the city has not yet been set. And until then, he said Tuesday, he will keep going to court, hoping that his family's house will be returned.

"I don't think it's right," he said. "No owner of a house in Philadelphia deserves this."