Not a US citizen, so apologies in advance if these questions come across as a bit ignorant...(probably because they kinda are):
If 80% kits are a problem because they don't have serial numbers and don't have background checks, why not just change the legislation to have them treated the same as a normal firearm so that they do require both?
How does treating a pistol with a brace as a short barrelled rifle change things in terms of the law? Does it make it illegal to own one? How does that make it worse than using an AR-15 with a longer barrel, but with a bigger magazine, larger calibre bullets, and being more accurate due to it being shoulder mounted?
Red flag laws, on their face, seem kinda open to abuse. I get that the idea is get guns out of the hands from people with mental issues, but what's to stop disgruntled family members (e.g. separated spouse) from using this to mess with someone? Or LEO's using this as a de facto method of disarming people they don't like?
If a court rules any of these unconstitutional, are they immediately struck down?
An 80% is ultimately just a partially milled block of aluminum. Where do you draw the line? 60%? 40%? 0%, where all blocks of aluminum are now regulated?
And nowadays there's been a surge in popularity of small desktop cnc machines, which can be had for a few hundred dollars. As long as the milling area is at least as large as a receiver, making a receiver from a block of aluminum is pretty trivial.
That all only addresses metal receivers - there's been a lot of strides made for 3D printed receivers, with people making Glock frames and AR receivers (fairly mature), and AK receivers (still being improved - functional but needs improvements for durability based on the last updates I saw).
Changing the definition of an 80% does absolutely nothing.
Braces:
So for this one we need to go back to the NFA and US v. Miller, a court case challenging it.
The NFA in it's original proposed text intended to address violence by the mafia that arose during prohibition, poaching, and keep handguns out of the hands of those pesky poor people.
To do that, it required registration and a tax stamp for machine guns, handguns, rifles and shotguns shorter than a specific length, and suppressors. All required a tax stamp of $200, which when adjusted for inflation would be in excess of $4000 nowadays, putting any out of the price range of the vast majority of people.
Now, the NRA managed to successfully get handguns removed from the NFA. But short barreled rifles (SBRs, barrel length < 16") and short barreled shotguns (SBS, barrel length <18') remained on the NFA. The sole reason those were on the NFA was to prevent those dirty poor people from getting around the paywall on handguns
So now we come to US v. Miller, in 1934. It was challenging the restrictions on short barreled shotguns. There were a number of procedural irregularities that went on, but the chief among them was the fact that the defense and their counsel never actually got a chance to travel to the supreme court and make their arguments, so the state side of the case made their argument unopposed. The resulting conclusion was that SBRs and SBSs could be restricted because the second amendment only protects arms useful for military/militia purposes.
But then you might ask, didn't the US use trench shotguns during WWI? And didn't the use shorter barrels than allowed? And I'd say yes. And the military currently uses rifles shorter than 16". But the Supreme Court only really made any sort of 2nd Amendment rulings again starting with DC v. Heller in 2008, and that had to do with handgun bans. There has not yet been a case that could revisit and perhaps overturn the ridiculous ruling made in Miller.
So now that the historical background is dealt with, why braces? The answer comes from what the ATF has defined as rifles. Specifically - a rifle must have a stock, and they ruled that a stabilizing brace is not a stock, so what would be an SBR with a stock would be a "pistol" with a brace. And, during the last administration, they in fact updated their guidance to clarify that even if you use a brace as a stock, it is still a brace, effectively neutering the SBR restrictions.
Unfortunately, shortly after the election, the ATF began to make moves in the opposite direction to, seemingly, get in the good graces of the incoming extremely anti-gun Biden administration.
Treating a pistol with a brace as an SBR pretty destroys the point of braces, as at that point you might as well just get the tax stamp, wait a year for ATF to check the box saying you're approved, and slap a stock on it. Plus actually hurting the community of disabled shooters who actually use it as a brace because they need that stabilization for actual pistols.
Red Flag Laws:
Your take on it is pretty much spot on. They're ripe for abuse.
Ruling Laws Unconstitutional:
If the Supreme Court rules them unconstitutional, it is immediately struck down with no exception. Though some lawa have provisions such that individual parts can be struck down without the the entire law being struck down.
If a lower court rules it unconstitutional, then it's only struck down as long as the state is not appealing the ruling, and they do not request a stay on the ruling, meaning it doesn't take effect unless the court appealed to upholds lower court ruling.
We've seen this multiple times in California in the past few years. One particular judge has been striking down California's gun laws left and right, the most notable of which was California's magazine ban on mags holding more than 10 rounds. That led to "Freedom Week", where the California residents were able to purchase standard capacity magazines. Shortly after though, the state requested a stay on the ruling, and appealed to the 9th Circuit, which traditionally has had a heavily anti-gun slant, because of some previous conventions of judicial nominations that were removed in the past four years, but this post is already too long to go into that. But the effective result is that we got lucky with the 3-judge panel at the 9th Circuit and they upheld the ruling, and after the state requested another stay, and now the case is proceeding to an 11-judge en banc panel. This is something requested by the judges of the circuit, in this case the majority anti-gun portion.
So what happens now? We wait, probably don't get lucky again, and the 9th Circuit rules the mag ban constitutional. At which point the plaintiff will almost certainly appeal to the Supreme Court. If they take it, and rule the mag ban unconstitutional, the law is struck down. And it will apply to all states, not just California where the specific law that was challenged was. Though there may be some steps to the other state's bans being struck down that I'm not knowledgeable about.
So this turned into way longer of a post than intended, and anyone reading this, please correct anything I got wrong here, because I was pretty much going off of memory, with a few quick Google searches to get years right.
Not a US citizen, so apologies in advance if these questions come across as a bit ignorant...(probably because they kinda are):
If 80% kits are a problem because they don't have serial numbers and don't have background checks, why not just change the legislation to have them treated the same as a normal firearm so that they do require both?
How does treating a pistol with a brace as a short barrelled rifle change things in terms of the law? Does it make it illegal to own one? How does that make it worse than using an AR-15 with a longer barrel, but with a bigger magazine, larger calibre bullets, and being more accurate due to it being shoulder mounted?
Red flag laws, on their face, seem kinda open to abuse. I get that the idea is get guns out of the hands from people with mental issues, but what's to stop disgruntled family members (e.g. separated spouse) from using this to mess with someone? Or LEO's using this as a de facto method of disarming people they don't like?
If a court rules any of these unconstitutional, are they immediately struck down?
80%'s:
An 80% is ultimately just a partially milled block of aluminum. Where do you draw the line? 60%? 40%? 0%, where all blocks of aluminum are now regulated?
And nowadays there's been a surge in popularity of small desktop cnc machines, which can be had for a few hundred dollars. As long as the milling area is at least as large as a receiver, making a receiver from a block of aluminum is pretty trivial.
That all only addresses metal receivers - there's been a lot of strides made for 3D printed receivers, with people making Glock frames and AR receivers (fairly mature), and AK receivers (still being improved - functional but needs improvements for durability based on the last updates I saw).
Changing the definition of an 80% does absolutely nothing.
Braces:
So for this one we need to go back to the NFA and US v. Miller, a court case challenging it.
The NFA in it's original proposed text intended to address violence by the mafia that arose during prohibition, poaching, and keep handguns out of the hands of those pesky poor people.
To do that, it required registration and a tax stamp for machine guns, handguns, rifles and shotguns shorter than a specific length, and suppressors. All required a tax stamp of $200, which when adjusted for inflation would be in excess of $4000 nowadays, putting any out of the price range of the vast majority of people.
Now, the NRA managed to successfully get handguns removed from the NFA. But short barreled rifles (SBRs, barrel length < 16") and short barreled shotguns (SBS, barrel length <18') remained on the NFA. The sole reason those were on the NFA was to prevent those dirty poor people from getting around the paywall on handguns
So now we come to US v. Miller, in 1934. It was challenging the restrictions on short barreled shotguns. There were a number of procedural irregularities that went on, but the chief among them was the fact that the defense and their counsel never actually got a chance to travel to the supreme court and make their arguments, so the state side of the case made their argument unopposed. The resulting conclusion was that SBRs and SBSs could be restricted because the second amendment only protects arms useful for military/militia purposes.
But then you might ask, didn't the US use trench shotguns during WWI? And didn't the use shorter barrels than allowed? And I'd say yes. And the military currently uses rifles shorter than 16". But the Supreme Court only really made any sort of 2nd Amendment rulings again starting with DC v. Heller in 2008, and that had to do with handgun bans. There has not yet been a case that could revisit and perhaps overturn the ridiculous ruling made in Miller.
So now that the historical background is dealt with, why braces? The answer comes from what the ATF has defined as rifles. Specifically - a rifle must have a stock, and they ruled that a stabilizing brace is not a stock, so what would be an SBR with a stock would be a "pistol" with a brace. And, during the last administration, they in fact updated their guidance to clarify that even if you use a brace as a stock, it is still a brace, effectively neutering the SBR restrictions.
Unfortunately, shortly after the election, the ATF began to make moves in the opposite direction to, seemingly, get in the good graces of the incoming extremely anti-gun Biden administration.
Treating a pistol with a brace as an SBR pretty destroys the point of braces, as at that point you might as well just get the tax stamp, wait a year for ATF to check the box saying you're approved, and slap a stock on it. Plus actually hurting the community of disabled shooters who actually use it as a brace because they need that stabilization for actual pistols.
Red Flag Laws:
Your take on it is pretty much spot on. They're ripe for abuse.
Ruling Laws Unconstitutional:
If the Supreme Court rules them unconstitutional, it is immediately struck down with no exception. Though some lawa have provisions such that individual parts can be struck down without the the entire law being struck down.
If a lower court rules it unconstitutional, then it's only struck down as long as the state is not appealing the ruling, and they do not request a stay on the ruling, meaning it doesn't take effect unless the court appealed to upholds lower court ruling.
We've seen this multiple times in California in the past few years. One particular judge has been striking down California's gun laws left and right, the most notable of which was California's magazine ban on mags holding more than 10 rounds. That led to "Freedom Week", where the California residents were able to purchase standard capacity magazines. Shortly after though, the state requested a stay on the ruling, and appealed to the 9th Circuit, which traditionally has had a heavily anti-gun slant, because of some previous conventions of judicial nominations that were removed in the past four years, but this post is already too long to go into that. But the effective result is that we got lucky with the 3-judge panel at the 9th Circuit and they upheld the ruling, and after the state requested another stay, and now the case is proceeding to an 11-judge en banc panel. This is something requested by the judges of the circuit, in this case the majority anti-gun portion.
So what happens now? We wait, probably don't get lucky again, and the 9th Circuit rules the mag ban constitutional. At which point the plaintiff will almost certainly appeal to the Supreme Court. If they take it, and rule the mag ban unconstitutional, the law is struck down. And it will apply to all states, not just California where the specific law that was challenged was. Though there may be some steps to the other state's bans being struck down that I'm not knowledgeable about.
So this turned into way longer of a post than intended, and anyone reading this, please correct anything I got wrong here, because I was pretty much going off of memory, with a few quick Google searches to get years right.