Sometimes it’s not just ornery neighbors complaining about traffic who hold up plans for new housing, but rival developers as well.

A Suffolk County Superior Court judge has ordered a major South End property owner to pay $11.6 million in damages, capping a decade of litigation, according to court records.

Arthur Leon and JACE Boston allegedly spent years abusing the city zoning appeals process, all in a bid to derail plans for a rival $20 million high-end condo project at 477 Harrison, next door to one of their own properties, court records show.

The attempt failed, but not before delaying plans for what are now the Jordan Lofts, driving the developer, John Holland, to the brink of bankruptcy.

Holland was forced to scale back some of his plans for pricier second-floor units, costing him $6 million, according to court filings, and even faced an outlandish criminal complaint from Leon, which was dismissed.

Leon claimed he had his own plans for a big mixed-use project, Holland testified during court proceedings.

Ironically, given his own alleged efforts at obstruction, Leon was concerned about Holland’s plans to build pricey penthouses, arguing it would attract rich people who would then object to his plans to redevelop his own building, Holland testified.

“There is no question that defendants’ unethical, unscrupulous, and unfair trade practices injured plaintiff and caused it to substantially delay and redesign the 477 Harrison development to its financial detriment,” wrote James Budreau, a Suffolk County Superior Court judge, in his ruling.

Ouch! Scott van Voorhis is a longtime Boston reporter specializing in real estate and is the publisher of Contrarian Boston.