A short-handed Supreme Court deadlocked 4-4 today on a decision that could have, in effect, made all 50 states right-to-work states with regard to government workers.

In upholding mandatory union fees for public sector employees, the split decision means a 39-year-old high court decision in favor of Detroit school teachers stands.

The plaintiffs in the current case had asked the justices to overturn the court’s 1977 decision to uphold union shops in public workplaces in a case known as Abood v. Detroit Board of Education.

Union opponents seemed to be on the brink of a watershed victory in this high-profile case. But Justice Antonin Scalia’s Feb. 13 death changed the dynamic, depriving conservatives of a fifth vote to allow workers to withhold union fees.

The case, known as Friedrichs v. California Teachers Association, offered the justices the option of allowing unions to continue requiring workers to pay for collective bargaining costs, but to simplify the process for workers who want to opt out of fees that pay for political activities.

Currently, states without a right-to-work law can require non-members to pay “fair share” fees. These fees cover what it costs the union to represent them in bargaining as long as the money doesn’t go for political purposes.

In the 1977 case, the court ruled that the fee system reasonably prevents non-members from “free riding,” since the union still has a legal duty to represent all workers. The high court has raised doubts about the viability of the ruling in two recent cases, but has stopped short of overturning it.

Opponents of the fee system want the justices to essentially convert those more liberal states with mandatory-fee laws into de-facto right-to-work states for public employee unions, where workers still covered by the union can pay nothing at all.

In Michigan, a historic labor stronghold, the loss of revenue at the Michigan Education Association teachers union has led to cuts in staff and more time spent urging members not to leave, said spokesman Doug Pratt in a recent interview with the Associated Press. That means fewer resources for bargaining contracts or efforts to reduce class size, curb standardized tests and increase school funding.

“It undermines our ability not only to bargain, but to operate as a collective,” Pratt said. “It’s about strength in numbers.”