Hypothetical Executive Illegal Order

"The War Powers Act, also known as the War Powers Resolution of 1973, requires the following: the President, upon sending troops into military action, must notify Congress within 48 hours that he has done so. The Resolution also forbids military personnel from remaining in a state of conflict for more than 60 days (including an additional 30 days for withdrawal). After that, the President must seek an additional authorization from Congress or a formal declaration of war."

What is the old saying, "Ours is not to wonder why, ours is but to do or die".

An order can be illegal and you preform it and not be held legally responsible. You have to KNOW the order to be illegal in order to refuse it. If you have doubts as to wither the order is legal then you must preform it.

Invading Canada? Lawful because you cannot prove it is not. Precedence has been set over history that congressional approval is not needed. Is it really lawful? That will be up to the courts to decide. Until they do, it is believed to be. Besides until they take Bieber back they are a hostile country in my book.

Depends on who you talk to. Some consider the continued occupation of Afghanistan to be an illegal order. Certain interrogation techniques advocated by the Bush administration. The use of drug money to move weapons between Iran and the Contras under President Reagan. The mobilization of Federal Troops to stand against local militias in the enforcement of potentially illegal actions like when Warren Harding used federal troops to support corporate managers during the "Battle of Blair Mountain" in 1921.
What is "illegal" can be highly subjective based on the mores and ethics of the age.
For example, if Obama were to use federal troops to side on disputes over fracking, eminent domain for oil pipelines, or property seizures based on GMO rulings, would you consider the action unilaterally illegal, or dependent on the side he took?