Jonathan Selbin’s interest in the Telephone Consumer Protection Act was piqued five years ago when a fellow attorney mentioned the endless robocalls banks were making to the cellphones of those who owed money.

Selbin, a partner at Lieff Cabraser Heimann & Bernstein, studied up on the law and realized that the automated debt collection calls — sometimes a dozen or more a day to one person — violated the federal law meant to protect consumers from phone harassment. “The calls are designed to bug people until they pay back the money,” Selbin said. “But it’s abusive to do it over and over again. The big banks were doing this for many years.”