1) Lower court rulings on assault weapons bans are meaningless. Lower courts are ignoring historical rulings, original intent, two recent rulings of the Supreme Court (Heller and McDonald), and the text of the 2nd Amendment itself. This is why some justices have said that the 2nd Amendment is becoming a 2nd class right. However, this has changed with the appointment of Justice Gorsuch – who has previously voted to overturn such laws. After his appointment, SCOTUS literally took the first gun rights case appealed to the court. Things have definitely changed – and Pres. Trump could very well get another appointment before they would hear an assault weapons case. We should also remember that lower courts were reversed in both Heller (2008) and McDonald (2010).
2) The Supreme Court ruled in 1939 (in Miller) that in order to be protected by the 2nd Amendment, a firearm had to be a weapon of war. Specifically, the court found that in order to be protected, a firearm had to have “value in the context of a militia”. This is the exact opposite of the argument that “weapons of war” should be banned. Lest you think that this is a gun rights view of Miller, Washington DC argued in Heller (2008) that their handgun ban was constitutional because handguns did not have “militia value”. The court rejected this argument by finding that they did indeed have such value.
3) Any assault weapons ban directly conflicts original intent. There is every indication that a majority of the current court believes that original intent is very important. It is an indisputable fact that the original intent of the 2nd Amendment included the ability of state to quickly raise a militia, and the ability of the people to both deter and respond to any tyrannical and unconstitutional government. The ability to own and possess a viable infantry rifle is essential to this purpose.
4) The explicit textual reference to militia. It's not just the original intent that supports the idea that individual weapons suitable for militia service are protected, the militia purpose is right there in the text!
5) Basic argument for the constitutionality of an assault weapons ban was rejected in rejected by SCOTUS in Heller (2008). The argument for an assault weapons ban is exactly the same as the argument Washington, DC made in support of their handgun ban: The banned firearm is too dangerous. There is one very important difference: When applied to an assault weapons ban it is much weaker. DC argued in Heller that because handguns are used in 63% of homicides, they are uniquely dangerous and a ban should be permitted. The high court rejected that argument. According to FBI stats, all kinds of rifles are used in less that 2% of homicides. Given that rifles are often weapons of opportunity, the so called assault weapons are likely used in less than 1% of homicides. If the Supreme Court refused to ban the most common homicide weapon, used in 63 times more murders than so called assault weapons the chance that they will ban these rifles because they are uniquely dangerous in nil.
6) Any “assault weapons ban” fails the common use test established in Heller. If government were to decide what firearms are and are not protected, there would effectively be no 2nd Amendment right. Therefore, in Heller (2008) the Supreme Court established a test to determine what firearms are and are not protected. They reasoned that, when called into militia service, citizens would bring firearms they chose to own for other lawful purposes. Therefore, the court ruled that any firearm commonly possessed for any lawful purpose is protected. So called assault weapons are the most popular firearms in the country, at least 40 million are legally owned in the US. They are used for target shooting, hunting and self defense. Every year they outsell all other rifles. If they are not in common use, no firearm is.
7) The level of protection SCOTUS will likely assign to the 2nd Amendment right makes an assault weapons ban impossible. The statement in the McDonald (2008) that the 2nd Amendment right is “essential to our system of ordered liberty” strongly hints that the high court will assign the highest level of constitutional protection to the 2nd Amendment right: Strict scrutiny. Indeed they could make this determination in the gun case they will hear next Spring. If they do, an assault weapons ban would be impossible. They would have to prove that there is a compelling need to regulate such firearms and that a ban is the least intrusive (upon the 2nd Amendment right) method of addressing that need. That would be an impossible task.