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Just what is a “single function” of a gun’s trigger?

The Supreme Court ruled today that a "bump stock" does not convert a semiautomatic firearm into a machine gun and is therefore legal. The key question is whether a rifle with a bump stock fires continuously or needs to be separately engaged for each round fired. As a result, the entire argument depends on a long and detailed exegesis of the phrase "single function of the trigger":

Bump firing is a balancing act. The shooter must maintain enough forward pressure to ensure that he will bump the trigger with sufficient force to engage it. But, if the shooter applies too much forward pressure, the rifle will not slide back far enough to allow the trigger to reset. The right balance produces a reciprocating motion that permits the shooter to repeatedly engage and release the trigger in rapid succession.

....According to ATF, all the shooter must do is keep his trigger finger stationary on the bump stock’s ledge and maintain constant forward pressure on the front grip to continue firing. The dissent offers similar reasoning.

This argument rests on the mistaken premise that there is a difference between a shooter flexing his finger to pull the trigger and a shooter pushing the firearm forward to bump the trigger against his stationary finger. ATF and the dissent seek to call the shooter’s initial trigger pull a “function of the trigger” while ignoring the subsequent “bumps” of the shooter’s finger against the trigger before every additional shot.

There's more along these lines. Much, much more. In fact, what strikes me about Clarence Thomas's majority opinion is that it's so lovingly crafted. I learned more about how a bump stock operates than in any news article I've ever read about it. It even includes diagrams showing how a semiautomatic trigger mechanism works!

It's pretty obvious that this is literally not a question of law at all. Is it a "single function of the trigger" if you merely keep the trigger depressed to fire multiple rounds but you have to rhythmically "bump" the rifle after every shot? What law is going to decide that?

Thomas's best argument, I think, has nothing to do with how a bump stock operates:

On more than 10 separate occasions over several administrations, ATF consistently concluded that rifles equipped with bump stocks cannot “automatically” fire more than one shot “by a single function of the trigger.”

....ATF abruptly reversed course in response to a mass shooting in Las Vegas, Nevada. In October 2017, a gunman fired on a crowd attending an outdoor music festival in Las Vegas, killing 58 people and wounding over 500 more. The gunman equipped his weapons with bump stocks, which allowed him to fire hundreds of rounds in a matter of minutes. This tragedy created tremendous political pressure to outlaw bump stocks nationwide.

This is true. It's pretty obvious that ATF changed its rules for purely political reasons, not because it genuinely believed bump stocks turned rifles into machine guns.

In any case, what happened is the usual thing. Even though this case is based on statutory language, not constitutional issues; and even though it depends on a very delicate interpretation of a single phrase; and even though both sides essentially agree on the particulars—despite all that, the conservatives all voted one way and the liberals the other way. And by an amazing coincidence, all nine justices decided that this delicate statutory interpretation matched their ideological preferences. How about that?

56 thoughts on “Just what is a “single function” of a gun’s trigger?

  1. FrankM

    There's a simple solution to this. Congress should amend the law on machine guns to include bump stocks. But they won't because...well, you know why. This is the real problem, ladies and gentlemen, not SCOTUS.

    1. dilbert dogbert

      The congress can use its power to tax to tax the stocks out of existence.
      The White Phosphorus Match Act of 1912, signed by President William Howard Taft on April 9, 1912, required manufacturers who used white phosphorus to register with district collectors of internal revenue and to file periodic notices and returns, levied a tax of two cents per hundred matches and required makers of white .

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    2. jdubs

      We know this is false. While the Court may prefer to pretend that this the case, they showed us in this very case that the actual language of the law doesnt matter.

      There is literally no way to write a law that is immune from a Court that is determined to tease apart and misinterpret in order to substitute its own policy preferences. This is obviously not the first time that this has occurred and its naive or disingenuous to pretend for this to be true.

  2. D_Ohrk_E1

    This is true. It's pretty obvious that ATF changed its rules for purely political reasons

    Sort of like how SCOTUS determined settled law isn't settled, or the other flip-flops used to execute majority power on political issues.

    What's notable about Thomas' opinion is how it needs diagrams to explain how it worked around the intent of the original law through literal interpretations of what is "automatic".

    It's silly to think that the reason why such weapons were banned 90 years ago was because legislators thought how the function of a gun is problematic and needed to be banned, rather than the function.

    1. MF

      Congress could have easily written the law to apply to any gun that an ATF tester could use to fire more than 20 bullets in 5 second or whatever other criteria it wished. The criteria Congress used was trigger pulls.

      The executive branch and courts are not supposed to rewrite the law to say what you think it should have said from the beginning.

      1. jdubs

        The court can easily re-interpret any word to change the clear language of the law. They did just that right in front of you while you copy/pasted their rationale and pretended that they would never do it again.

        In your disingenuous example, we just reinterpret what 'fire' means. Its so easy.

        I have to assume you are being disingenuous and acting as a loyal repeater of things you are told to repeat. Cant actually be this naive.

      2. D_Ohrk_E1

        Gun Control Act from 1968:
        "MACHINEGUN.—The term 'machinegun' means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any combination of parts designed and intended for use in converting a weapon into a machinegun"

        A bump stock is designed to make a single press of the trigger to fire repeatedly, by way of bumping the trigger against the already pressed finger.

        Call me stupid, but this is the same work-around Conservatism uses in the 2nd Amendment to claim that the right to own firearms is absolutely, constitutionally protected.

  3. raoul

    It is quite disingenuous to claim a bump stock does not convert an assault weapon to a machine gun- that’s the purpose of the device, nothing more, nothing less. If I had written the dissent I would just have listed the many hundreds of people who were injured or killed in Las Vegas in 10 or so minutes.

    1. golack

      Oh no....just ask the manufacturers. It's just an aid for those with weak finger strength, ADA compliance and all that....
      https://slate.com/news-and-politics/2024/06/supreme-court-opinions-clarence-thomas-bump-stocks-gun-fetishist.html
      "This account is dead wrong: ATF took a careful, case-by-case view of different bump stock–like devices as gunmakers developed them, deeming some permissible and others unlawful. The gun industry pushed these devices into the mainstream by deceiving ATF about their purpose; in one case, for instance, a manufacturer won approval from the agency by claiming a bump stock was designed to accommodate people with limited hand strength—then turned around and marketed it as the next best thing to a machine gun."

    2. Jerry O'Brien

      Yes. I think it's plainly true that the bump stock provides the repeated "trigger action." The shooter doesn't have to do anything but maintain a constant pressure after the first trigger pull. I'm not a gun expert, but I'm not convinced that the majority in this case have any deeper understanding of the physical facts.

  4. DeadEndSutton

    A lot of the discussion is about using bump stocks to turn an semi-automatic rifle into a machine gun. My worry is that the gun lobbyists will someday decide that an automatic rifle (AR-15) in full automatic mode (no bump stocks) is not a machine gun and therefore should be legal. To them, a machine gun is planted on the ground, is fed by a belt of bullets, and is not carried around like a rifle.

    1. MF

      Machine gun is defined in the statute.

      In my opinion it violates the Second Amendment, but the meaning of the statute is clear.

  5. DFPaul

    Remember, "conservatives" say this level of detail in regulations is what only Congress should be writing, not regulators told by Congress to fix stuff in general.

  6. iamr4man

    No matter how you explain it it’s hard to understand but easy to understand once you’ve experienced it. You’ve probably experienced it with tactile buttons you push that pop back. If you put just the right pressure it will pop back two or three times. You can actually do it with a semi-automatic gun without a bump stock. The bump stock makes it easy and will allow you to shoot several shots with a relative amount of accuracy.
    The original interpretation by the ATF was controversial and, really, absurd. Bump stocks convert semi automatic weapons into automatic weapons. It’s a trick designed to get around the law banning automatic weapons. The law was meant to ban automatic weapons not limit the times you pull a trigger.
    https://youtu.be/vQcE6CW91UU?si=1tfkKVWSRRpV3l0j

  7. Salamander

    Clearly, the wingnut faction of the once-Supreme Court knows as much about firearm effects as it does about the female reproductive system. And medical insurance.

  8. larkin

    It sounds like ATF updated its opinion about bump stocks once there was evidence that they are just as destructive as automatics, even if they are not in the category of automatics. Doesn't seem like politics, just updating policies based on new evidence.
    After 9/11 showed that planes could be used like missiles, we tightened security on planes, not because we believed that planes literally are missiles, but because there was real-world evidence that they'd be used to cause the same kind of damage.

  9. KJK

    Apparently, a bump stock can allow a semi-automatic rifle's rate of fire to be similar to an automatic weapon (like between 400 and 800 rounds per minute)

    Sure sounds like a fucking machine gun. Clyde Barrow would have appreciated the technology, though he may have stuck with his BAR.

  10. lower-case

    scotus says a bump stock-enhanced rifle can't be classified as an automatic weapon

    but a fertilized egg can be classified as a person

  11. Heysus

    Left is right, up is down, and the whole repulsive world is demented and we must live among them, unwillingly, or get shot.

  12. cmayo

    Oh please. Give me a break.

    Does anyone believe that the first 10 instances of the ATF concluding that a bump stock did not a machine gun make were NOT motivated by political concerns? The first time it came up was in the Bush administration and of course they allowed it.

    It's also notable that Paul fucking Ryan questioned why the ATF allowed bump stocks to slide (or bump) in the first place, in 2017.

    The NRA said, and I quote, "“The NRA believes that devices designed to allow semi-automatic rifles to function like fully-automatic rifles should be subject to additional regulations."

    It's also notable that the bump stock ban from the ATF occurred under Trump and took effect in 2018.

    It's only seen as political now because there's a Democrat in the White House and it's easier for Republicans to use this as a way to manufacture outrage and rile up their base.

  13. clawback

    "This tragedy created tremendous political pressure to outlaw bump stocks nationwide."

    No, the tragedy showed everyone except Clarence Thomas and Kevin Drum that bump stocks, which had then been shown capable of injuring and killing hundreds of people within minutes, are effectively machine guns. That ATF recognized their previous error is to their credit. That Clarence Thomas and Kevin Drum continue to insist otherwise in the face of this evidence is ... not to their credit.

    1. Austin

      Now, now, Kevin has to be able to look his decent Orange County Republican friends in the eye over lunch next week. “It is difficult to get a man to understand something, when his social connections depend on him not understanding it.” Hope nobody brings a now-legal bump stock anywhere in Orange County soon.

  14. Five Parrots in a Shoe

    Ever since the Dobbs ruling Ds have been consistently outperforming polls in elections.

    If SCOTUS had ruled differently in this case it might have negated the Dobbs effect: gun fondlers are not rational, but they are utterly paranoid. An opposite ruling in this case would have fed that paranoia. I'll be happy if more of them feel like they can stay home in November.

  15. lower-case

    wapo:

    Texas high court declines to decide if embryos are people or property

    The case that was before the state Supreme Court, stemming from a couple’s divorce, could have had significant implications for IVF in Texas.

    HOUSTON — The Texas Supreme Court on Friday declined to consider whether frozen embryos are people or property in the eyes of the law — a ruling that could have had dramatic consequences in a state where in vitro fertilization is booming.

    when it comes time to throw a slutty slut slut slut in prison, we can all agree that life begins at conception

    but when two good christian folk are fighting over a frozen fertilized egg, and we need to decide who gets them eggs, well... one way or t'other some decent god-fearin' folk is gunna git mighty upset, so gotta be gosh darn keerful 'bout 'dat kinda judgin' bidness... amirite?

    1. Austin

      So then what lower ruling was left in place? Somebody must’ve already ruled they are people or property in a lower court, no?

  16. Austin

    Thank god SCOTUS saw that Congress, when banning machineguns that fire off 950 rounds per minute, never intended for bump stocks that fire off 800 rounds per minute to also be banned. That slower rate of fire obviously gives potential targets/victims ample time to run/hide/fight back. Someone hopefully will test this theory on the plaza in front of the SCOTUS building, before 6 of 9 justices burn in hell forever for their morally bankrupt pedantry.

    1. MF

      In think you miss the point.

      Congress wrote a clear and specific law. Under that law bump stocks are not machine guns. If it is necessary to change that definition it must be drive by Congress, not the executive branch.

      The issue is separation of powers. It means Trump in his second coming will not have the power to have his agencies ignore the clear meaning of the law by redefining terms defined by lawmakers. Think about that.

      1. jdubs

        ACSHUALLY THE COURT MISINTERPRETING LANGUAGE TO ADVANCE EXTREME CONSERVATIVE POSITIONS IS GOOD FOR US BECAUSE TRUMP!!!! CHECKMATE LIBZ!!!

        Lol, so dumb.

      2. iamr4man

        The clear intent of the law was to ban automatic weapons. So some person came up with a semantic workaround and said “nyah, nyah, nyah!” If your kid tried something similar you would say “nice try kid” and take it away.

  17. Jim Carey

    "And by an amazing coincidence, all nine justices decided that this delicate statutory interpretation matched their ideological preferences."

    Define "ideology." Never mind, I'll do it.

    A subject is a group or individual within a larger social system. The subject has a within-system circle of influence, and a within-system circle of concern. If the subject's circle of influence is encompassed within the subject's circle of concern, then the subject is grounded in reality. If the subject's circle of influence extends beyond the subject's circle of concern, then the subject's circle of concern is an ideology.

    Translation: three real justices are grounded in reality, and the delicate statutory interpretation matched the ideological preferences of six phony justices.

    Thanks Mitch!

  18. Adam Strange

    "And by an amazing coincidence, all nine justices decided that this delicate statutory interpretation matched their ideological preferences."

    This is the way the world turns.

    Start with your conclusions based on your personal bias, then find the reasons which support your biases.

    Let me say that the discovery of the Scientific Method transformed human existence, but it could stand to be applied much oftener that it is.

  19. KenSchulz

    The right balance produces a reciprocating motion that permits the shooter to repeatedly engage and release the trigger in rapid succession.

    This is incorrect — the shooter does not ‘engage and release the trigger’; the trigger presses and relieves against the shooter’s stationary finger. The bump stock turns the weapon (and the shooter’s forearm) into a spring-mass oscillator, kept in oscillation by the recoil of firing. No voluntary movement of the shooter occurs at anywhere near the rate of fire of the weapon; that is what makes it, functionally, fully automatic. Had the law read pull of the trigger, bump stocks would clearly be illegal. Better, the law should simply ban weapons capable of being fired above a specified rate, without specifying a mechanism. A Congress reflective of the people’s will would fix the law.

    1. Jerry O'Brien

      Thanks for a very clear explanation. The members of the majority on the Supreme Court either don't grasp these mechanical basics, or want to pretend they don't grasp them.

    2. Yehouda

      "Better, the law should simply ban weapons capable of being fired above a specified rate, "

      "One bullet per deliberate action of the shooter" is really what you want.

      1. Five Parrots in a Shoe

        No. A restriction of one round every two seconds - or some such figure - would be harder to for bad actors in the firearm industry to work around.
        A fully automatic weapon that fires only slowly would be useless to potential mass shooters. Which is the point of such a regulation.

        1. Yehouda

          The problem is that such restriction will need to define what "automatic" means. The original law used "single function of the trigger" for that, which is misguided.

          If you mean passing an act that restricts all arms to less than one-per-x-second, that would be much more difficult.

          1. KenSchulz

            My own inclination is to permit only weapons with fixed-size permanent magazines which must be reloaded one round at a time, with a very small capacity, perhaps 3-5 rounds (OK, an exception for the classic six-shooter).

            1. iamr4man

              I agree with this though I’d probably allow a larger capacity magazine. Perhaps as high as eight.
              Also, your description of how a bump stock works is excellent.

  20. NeilWilson

    I am not sure I understand the issue here.
    Why is a machine gun not an "ARM"?

    If the bump stock turns an "ARM" like a semi-automatic rifle into a "NOT ARM" then .... what?

    My 2nd Amendment right "SHALL NOT BE INFRINGED".

    I don't even know why I have to certify that I am not on drugs to exercise my GOD GIVEN RIGHT.

    I can vote when I am on drugs and the right to vote is not in the Constitution.

    Once you take away my right to nuclear bombs, machine guns, and ICBMs aren't we just on a slippery slope until you take away my hunting rifle?

  21. Jimbo

    It's not surprising that the 6 conservative SCOTUS justices would employ the logic of medieval scholastics to determine how many angels can dance on the head of a pin, in this case a firing pin. However, the excruciating over-explaining in the majority opinion obscures their over-arching conundrum, which is that they know that they will now be accessories to future mass murders that result from the use of bump stocks. Perhaps not legally, but ethically they will responsible for what is known in US law as depraved-heart murder, or depraved-indifference murder, which is a type of murder where an individual acts with a "depraved indifference" to human life and where such act results in a death, despite that individual not explicitly intending to kill. These types of murderd occur when individuals knowingly commit acts that they know results in an unusually high risk of causing death or serious bodily harm to a person. If the risk of death or bodily harm is great enough, ignoring it demonstrates a "depraved indifference" to human life.

  22. jdubs

    " It's pretty obvious that ATF changed its rules for purely political reasons, not because it genuinely believed bump stocks turned rifles into machine guns."

    ‐‐-------

    This is not at all obvious. Your assumed ability to peer into the minds of the ATF powers that be and divine their pure thoughts is obviously not an actual ability that you possess.

    Its just as obvious that after the massacre, the ATF realized that bump stocks did turn weapons into machine guns and should be included as a banned item.

    The ATF banned the first bump stock device in 2005/6, then changed their mind several years later and allowed then to be used. Then they changed their minds again in 2017. Knowing what they truly thought at any point is impossible. We only know what they did, we can't divine their intentions and thoughts.

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