Last week, a lawyer for a Louisiana teachers’ union wrote a letter to 95 private schools that have agreed to participate in the Pelican State’s new school voucher program. His message? That vouchers are unconstitutional and if schools accept them, “We will have no alternative other than to institute litigation against [you].”

Nice little private school you got there. It’d be a shame if an angry education monopoly sunk it with groundless lawsuits.

The letter demonstrates the union’s desperation. Teachers’ unions hate vouchers because they require schools to compete on cost and quality, which means they’re unlikely to increase union rolls by hiring extra teachers. And the unions have every reason to be worried about Louisiana’s initiative: More than 10,000 kids have already signed up for the four-month-old program, five times as many as the state superintendent expected to sign up by this point.

Bill Maurer of the Institute for Justice, a libertarian public interest law firm, tells me that this legal intimidation is “unprecedented.” The Institute for Justice and the Alliance for School Choice have retained a lawyer to defend these schools pro bono.

Louisianans’ interest in vouchers grew out of the devastation wrought by Hurricane Katrina. In the wake of the storm, which destroyed many of New Orleans’ schools, state legislators instituted a series of education reforms targeting students in the impoverished city. One of the reforms was a New Orleans-specific voucher program; another allowed independently run, largely non-unionized public charter schools to open in the city. Those reforms have proven both popular and successful. Based on this success, Gov. Bobby Jindal made passing a statewide school choice bill one of his top priorities after winning re-election with two-thirds of the vote in 2011.

“This is not about the next election. This is not about the next poll. This is about the next generation,” Jindal repeatedly told state legislators. “If we want to preserve the American Dream for our children, if we want them to do better than we did, then it is important they get a great education.”

But, as Jindal knows, it’s hard for Louisiana students to get great educations when the state forces them to attend particular schools regardless of quality, expense, or family fit. And Louisiana’s schools are some of the worst in the country: the state ranks 49th in student performance on the well-respected National Assessment of Educational Progress. Nearly half the state’s fourth graders essentially can’t read, for example, while more than a quarter can barely add and subtract.

In April, Gov. Jindal signed into law a statewide voucher program. It applies to nearly half the state’s kids (to qualify, students must be slated to attend low-performing schools and come from families that can’t afford better private schools).

Two unions and the Louisiana School Boards Association have sued the state, arguing that the new voucher program is unconstitutional. Fortunately, Louisiana judges have refused union requests to delay implementing the program until the lawsuits are settled.

Unfortunately, Louisiana’s union leaders have decided their future rests on denying a better one to Louisiana kids.

Joy Pullmann is managing editor of School Reform News and an education research fellow at The Heartland Institute.