18 U.S.C. §1951(a)(2) defines extortion as the obtaining of property from another, with his consent, induced by wrongful use of actual or threatened force, violence, or fear, or under color of official right.
Canadian criminal code section 346(1) says "[e]very one commits extortion who, without reasonable justification or excuse and with intent to obtain anything, by threats, accusations, menaces or violence induces or attempts to induce any person, whether or not he is the person threatened, accused or menaced or to whom violence is shown, to do anything or cause anything to be done."
There are essentially three elements to the offense of extortion. (1) Coercion was employed, (2) without reasonable justification or excuse, and (3) to obtain property in the United States or anything in Canada.
The coercion element of the extortion statutes includes threats, menaces, violence, fear, accusations, or official right.
At common-law extortion was a "separate public official offense punishing the conduct of public officials who sought personal financial gain under colour of their office. It has since been statutorily expanded in some jurisdictions, such as Canada, to include more familiar forms of blackmail." R v. Davis,  3 SCR 759.
At common law, extortion was an offense committed by a public official who took 'by colour of his office' money that was not due to him for the performance of his official duties. A demand, or request, by the public official was not an element of the offense. Extortion by the public official was the rough equivalent of what we would now describe as 'taking a bribe.' Evans v. United States, 504 U.S. 255 (1992).
As we explained above, our construction of the statute is informed by the common-law tradition from which the term of art was drawn and understood. We hold today that the Government need only show that a public official has obtained a payment to which he was not entitled, knowing that the payment was made in return for official acts.
In Canada there is a reasonable justification or excuse clause contained within the extortion statutes. In the United States, the threat needs to be one of force, or under color of official right. If a person is justified in their action, then they have done nothing wrongful. A person has reasonable justification or excuse if he is not demanding more than is due2 and he is using his or her own power or property to negotiate and not trespassing on other people's power.
The importance of the line between public and private beneficiaries for common law and Hobbs Act extortion is confirmed by our own case law, which is completely barren of an example of extortion under color of official right undertaken for the sole benefit of the Government.
Extortion mainly depends on what you are negotiating with. A person can negotiate with their own property and power. But a person cannot negotiate with violence or with the Government's property and power, unless the benefit is solely for the Government. The crime at common-law was essentially a trespass on the King's coercion.