ALBANY – Lawyers for one of New York’s biggest landlords argued yesterday before the Court of Appeals that its interpretation of rent deregulation statutes and its practice of decontrolling rents on some apartments while accepting tax breaks to make building improvements is entirely proper.

Units significantly improved through tens of thousands of dollars’ worth of investments by landlords should be subject to luxury decontrol as established by the Legislature and not rent at “well, well, well below market” rates in a regulated marketplace, Jay B. Kasner argued on behalf of PCV ST Owner L.P., the general partner of Tishman Speyer Properties.