Baristas represented by Workers United walked out for the day at more than 100 locations to protest alleged union busting.
Sen. Bernie Sanders said he looks forward to hearing from Schultz “as to when he intends to end his illegal anti-union activities.”
The chain's famous CEO also faces a possible subpoena before the U.S. Senate to address union-busting allegations.
The labor board judge said a broad ruling was necessary to ensure Starbucks stopped “infringing in any other manner on rights guaranteed employees.”
The senator wants the Starbucks co-founder under oath for questioning about the company's anti-union campaign.
The coffee-olive oil concoction has provoked both amusement and curiosity among Italians.
Faced with extensive allegations of union-busting, the coffee chain said it would rather send a different executive to the Senate hearing.
A three-member panel found that the coffee chain repeatedly violated the law while workers were organizing in Philadelphia.
The labor movement added 273,000 members, but couldn’t keep pace with nonunion job growth.
They are seeking a rare order that would force Starbucks to bargain with workers at a Florida store where the union lost an election.