The government's order led to a swift backlash, with all other public transport workers declaring immediate strikes that forced Athenians to walk or take taxis through thunderstorms Thursday and Friday. Traffic slowed to a crawl, and commutes took up to three times as long as normal.
Defending the government's, government spokesman Simos Kedikoglou insisted the new austerity measures must be implemented.
"We are a society, an economy, at a very difficult time," he said. "People can't ask for exceptions."
The civil mobilization law, amended in 2007 to deal with "peacetime emergencies," has now been used nine times since the 1974 collapse of a military dictatorship in Greece - three of those in anti-austerity strikes over the past two years. Defying the order to return to work can lead to arrest and jail terms of between three months and five years.
Unions and the radical left main opposition Syriza party accused the government of dictatorial tactics.
"It's a new coup against this country's constitution to mobilize working people on strike on the subway with military-style methods," Syriza lawmaker Dimitris Stratoulis said late Thursday.
Considered an extreme measure, use of the law usually sparks an outcry but does tend to end a strike. It has been used in the past to end a protracted strike by garbage collectors, with the government at the time citing public health concerns, and to end a fuel truck strike that had caused major gasoline shortages.
The strike has been met with a mixture of understanding and exasperation from commuters, many of whom have also suffered deep income cuts.
Data released by Greece's statistical authority Friday showed that households' disposable income dropped 10.6 percent in the third quarter of 2012, compared with a year before. The authority said salaries fell 11.3 percentand social benefits received by households decreased 10.2 percent â¿¿ while taxes on household income and wealth increased 17.7 percent.