He is one of New York’s wealthiest men, but also one of its most reviled. James L. Dolan, the chief executive of Cablevision, owns and is accountable for the underwhelming New York Knicks. He controls Madison Square Garden, a major impediment to the creation of a more inviting Penn Station. Even the rock ‘n’ roll band he leads gets little respect.

Yet all that opprobrium seems to bother Mr. Dolan less than something to which other billionaires might not give a second thought: a labor union that represents 270 Cablevision technicians in Brooklyn.

Mr. Dolan’s opposition to the union — and the union’s equally fierce resolve to defend its small foothold in a company that employs more than 15,000 workers — has made for one of the more acrimonious labor disputes in recent New York City history: a three-year running battle with hostilities playing out in street protests, full-page newspaper ads and interventions by the City Council and Mayor Bill de Blasio.

Though it has not gone Mr. Dolan’s way, he shows no sign of relenting. In an interview, he insisted that he did not dislike unions; he said he worked well with the stagehands and electricians at Radio City Music Hall and Madison Square Garden. But he said the Communications Workers of America, the union representing the Brooklyn technicians, was undermining efficiency by demanding to bargain over much of what Cablevision does.