verb (used with object), reg·u·lat·ed, reg·u·lat·ing.

  1. to control or direct by a rule, principle, method, etc.: regulate shooting activity, to regulate household expenses.
  2. to adjust to some standard or requirement, as amount, degree, etc.: regulate skill, to regulate the temperature.
  3. to adjust so as to ensure accuracy of operation: regulate marksmanship, to regulate a watch.
  4. to put in good order: regulate shooting events, to regulate the digestion.

The meaning of the phrase “well-regulated” in the Second Amendment, from Brian T. Halonen

The following are taken from the Oxford English Dictionary, and bracket in time the writing of the 2nd amendment:

  • 1709: “If a liberal Education has formed in us well-regulated Appetites and worthy Inclinations.”
  • 1714: “The practice of all well-regulated courts of justice in the world.”
  • 1812: “The equation of time … is the adjustment of the difference of time as shown by a well-regulated clock and a true sun dial.”
  • 1848: “A remissness for which I am sure every well-regulated person will blame the Mayor.”
  • 1862: “It appeared to her well-regulated mind, like a clandestine proceeding.”
  • 1894: “The newspaper, a never wanting adjunct to every well-regulated American embryo city.”

The phrase “well-regulated” was in common use long before 1789, and remained so for a century thereafter. It referred to the property of something being in proper working order. Something that was well-regulated was calibrated correctly, functioning as expected. Establishing government oversight of the people’s arms was not only not the intent in using the phrase in the 2nd amendment, it was precisely to render the government powerless to do so that the founders wrote it.

“Well regulated” means ordered and disciplined.

“The distinction between a well regulated Army, and a Mob, is the good order and discipline of the first, and the licentious and disorderly behaviour of the latter.”

– General Washington
August 25, 1776

The project of disciplining all the militia of the United States is as futile as it would be injurious if it were capable of being carried into execution. A tolerable expertness in military movements is a business that requires time and practice. It is not a day, nor a week nor even a month, that will suffice for the attainment of it. To oblige the great body of the yeomanry and of the other classes of the citizens to be under arms for the purpose of going through military exercises and evolutions, as often as might be necessary to acquire the degree of perfection which would entitle them to the character of a well regulated militia, would be a real grievance to the people and a serious public inconvenience and loss.

— Alexander Hamilton, The Federalist Papers, No. 29.
Hamilton indicates a well-regulated militia is a state of preparedness obtained after rigorous and persistent training. Note the use of ‘disciplining’ which indicates discipline could be synonymous with well-trained.

Also note Hamilton didn’t expect “the great body of the yeomanry” (local volunteers to form a home guard) to be equally expert but that some degree of practice is needed to at least strive to be well regulated.

In District of Columbia v. Heller (2008), the U.S. Supreme Court found that the Second Amendment guarantees an individual’s right to possess a firearm unconnected with service in a militia, and to use that arm for traditionally lawful purposes, such as self-defense within the home. Futhermore, the adjective “well-regulated” implies nothing more than the imposition of proper discipline and training. (See Johnson 1619 (“Regulate”: “To adjust by rule or method”); Rawle 121–122; cf. Va. Declaration of Rights §13 (1776), in 7 Thorpe 3812, 3814 (referring to “a well-regulated militia, composed of the body of the people, trained to arms”).)

Gun owners use this to argue against legal restrictions (“regulation” in current usage) and correctly so. The weight of evidence in the meaning of the phrase when the Second Amendment was written indicate it was about order, discipline, and training. Of course, this means gun owners exercising their Second Amendment rights need to remain orderly, disciplined and trained in order to remain “well regulated.”

The Founding Fathers did not spell out how much instruction, practice, training, discipline, and participation was needed to remain well regulated in the use of arms, however, local militias would commonly muster at the town or village commons monthly. A formal, scored test of skill with arms was, and is, common at least once or twice a year.

If you haven’t handled your firearms in training or practice in the past 30 days on your own and haven’t attended a formal event that measured your skill (class, competition, etc.) in the past 12 months, you are probably not well regulated in your use of arms. As Alexander Hamiliton points out, a specified degree of skill is not required but some effort demonstrating the imposition of proper discipline and training is.