The city of Detroit is in the process of filing 700 lawsuits by Thursday against landlords and housing investors in a new effort to collect unpaid property taxes on abandoned homes that have already been forfeited to the government.

By the end of November, the litigation sweep may hit 1,500 companies and investors whose abandonment of Detroit homes is blamed for contributing to the city's neighborhood blight epidemic.

Motor City Law PLLC, working on behalf of the city, has filed more than 60 lawsuits since Aug. 18 in Wayne County Circuit Court and the rest of the lawsuits will be filed before a Thursday statute of limitations deadline, Detroit attorney Andrew Munro told Crain's.

The lawsuits target banks, land speculators, limited liability corporations and individuals with three or more rental properties in Detroit who typically buy the homes for cheap at a Wayne County auction and then eventually stop paying property tax bills and lose the home in foreclosure, Munro said.

"The targets are the landlords and the people who are abusing the auction system," Munro said Monday.

A second wave of 800 lawsuits will be filed over the next three months.

"There's a statute of limitations issue, which is why we broke it up in two tranches," Munro said.

A year ago, Detroit sued more than 500 banks and LLCs that had an ownership stake in houses that sold at auction for less than what was owed in property taxes.

Last year's stack of lawsuits has netted more than $5 million in judgments, "while many cases are still being litigated," said Eli Savit, senior adviser and counsel to Mayor Mike Duggan.

"The city's outside counsel is in the process of collecting on those judgments," Savit said in a statement to Crain's.

City officials did not have an exact figure Monday on how much property tax is owed by the 700 property owners who are being sued this week.

"We are still going through the data of all of the property subject to this year's lawsuits, but the amount of delinquent taxes involved is in the tens of millions," Savit said.

The 69 lawsuits filed since Aug. 18 in circuit court were for tax bills exceeding $25,000 each. Unpaid tax bills for less than $25,000 will be filed in district court.

The unpaid taxes date back years as the properties were auctioned off by the Wayne County Treasurer's Office between 2013 and 2016 or sent to the Detroit Land Bank Authority, which oversees demolitions if homes can't rehabilitated or sold.

In most Michigan counties, the treasurer's office recoups the unpaid taxes on a home that was seized in foreclosure through sale of the home at an auction. But in Detroit's depressed housing market, where homes sell at auction for as little as a few hundred dollars, the tax bills for three or more years assessed at a higher value can be thousands of dollars.

"For instance, out in Oakland County, they don't have this problem," Munro said. "In Wayne County, it's a huge problem."

The lawsuits Munro's firm has filed come attached with a letter advising the defendants to call and settle the debt, plus attorney fees.

"There is no legitimate debate that assessed owners are personally liable for uncollected taxes under Michigan law," the letter says. "Should you defend the complaint on the basis that there is no personal liability for property taxes the court may find such a defense unwarranted and frivolous."

The lawsuits indicate the former property owners have no recourse for lowering their unpaid tax debt because they're now "time barred from filing an appeal" with Detroit's Board of Review or the Michigan Tax Tribunal.

Motor City Law PLLC has set up a call center for tax collections inside a building on West Seven Mile Road where the small firm is based.

City officials said individual homeowners would not be targeted by the lawsuits for unpaid taxes.

But the lawsuits do seek to establish a legal means for going after investors who buy cheap homes at auction and either rent them out and not pay the taxes or walk away from the house because it's damaged beyond repair, Munro said.

"That's the kind of behavior the city is trying to change," he said.

Munro said suing past property owners for the balance of unpaid taxes after an auction is a concept he pitched to former Emergency Manager Kevyn Orr during Detroit's 2013-14 bankruptcy.

"This is a program no other city has ever done in the state of Michigan," Munro told Crain's. "It took a while to convince everybody that it's viable, but it is."