Boards have the power to decide any and everything in a corporate structure. They are, in fact, the only way that a decision of the corporation is made and made official.
I'm not sure what legality has to do with any of this. A corporation is a legal structure, and a board is its decision-making body. If you're talking about criminal charges or disputes between parties about who's got the power or authority to do something, then those are decided by courts, but in a civil context courts don't originate decisions. Courts ratify decisions or choose between dissenting views on what the decision is.