Supreme Court justices could deliver three harsh blows during the current term to Big Labor. One could undermine much of what President Obama has done for unions, and another could prohibit one of labor's main organizing tactics. A third endangers a different organizing tactic.

The case that has drawn the most attention is Noel Canning v. National Labor Relations Board. That will determine whether Obama's 2012 recess appointments to the NLRB — and most of its actions since then — were constitutional.

A potentially bigger deal for unions is Unite Here Local 355 v. Mulhall. The Court could find that a major union tactic — striking deals with management before organizing workers — amounts to bribery.

On Tuesday, the court announced that it will hear Harris v. Quinn, which deals with whether a state can declare home health care workers eligible for organizing.

Mulhall will be heard in November. Dates haven't been set for the others.

The cases underscore how much Big Labor relies on a favorable legal and regulatory environment. That’s why they came out so strongly for Obama twice.

But despite two Supreme Court picks, Obama hasn't been able to undo the court's 5-4 conservative majority.

Noel Canning is bigger than just labor law. It deals with when exactly a president may make “recess appointments.”

The Constitution allows a president to make such appointments when the Senate is out. This was intended for emergencies, but many presidents have abused the power.

Obama took it a step further in January 2012 when he made three recess appointments to the NLRB, which enforces labor law. He did this even though the Senate said it was not in recess.

A lower federal court ruled the appointments unconstitutional this year in January. That meant the NLRB has lacked a valid quorum since Obama's action.

Upholding the ruling could limit abuses of executive power by strengthening the Senate’s role in approving presidential appointments.

A May study by the National Right to Work Legal Defense Foundation found that upholding the ruling could also invalidate more than 15,000 NLRB decisions, including 673 that set precedents.

That would be a setback for Big Labor, but only a temporary one, as the Senate approved a majority-Democrat NLRB in August, so the agency is back in business.

Mulhall could be more far-reaching. It involves a union helping a Louisiana “gaming” company by running ads in favor of a pro-gambling ballot initiative.

In exchange, the business cooperated with the union’s bid to organize its workers by turning over their contact information, among other assistance.

To sweeten the deal, the union promised the company “labor peace,” meaning no strikes or other disruptions.

One employee objected to his contact details being given away. A court ruled the information amounted to a “thing of value” for the union and therefore amounts to a bribe.

Such “neutrality agreements” with management are an increasingly common labor tactic. One law review article found them successful 78 percent of the time.

In Harris v. Quinn, Illinois home health care workers allege their designation as state employees violates their First Amendment rights by potentially forcing them to pay union dues.

The cases are hard to handicap, but the justices showed last year that they are willing to put strict limits on union power.

Knox v. Service Employees International Union struck down a key union political funding tactic that forced extra dues payments near an election.

Justice Alito’s majority opinion said that compulsory union fees "constitute a form of compelled speech and association that imposes a significant impingement on First Amendment rights.”

That is a court willing to fundamentally rethink labor law. Big Labor has reason to be worried.