Under U.S. federal law:
It’s illegal “to develop, produce, otherwise acquire, transfer directly or indirectly, receive, stockpile, retain, own, possess, or use, or threaten to use, any chemical weapon” (U.S. 18 § 229) with the penalty being a fine, imprisonment “for any term of years”, or both; and the death penalty or imprisonment for life if the violation results in the death of another person (18 U.S.C. § 229A).
Any person who “knowingly develops, produces, stockpiles, transfers, acquires, retains, or possesses any biological agent, toxin, or delivery system for use as a weapon, or knowingly assists a foreign state or any organization to do so, or attempts, threatens, or conspires to do the same, shall be fined under this title or imprisoned for life or any term of years, or both”. Additionally, knowingly possessing “any biological agent, toxin, or delivery system of a type or in a quantity that, under the circumstances, is not reasonably justified by a prophylactic, protective, bona fide research, or other peaceful purpose, shall be fined under this title, imprisoned not more than 10 years, or both” (18 U.S. Code § 175).
It’s illegal to “knowingly participate in the development of, manufacture, produce, transfer, acquire, receive, possess, import, export, or use, or possess and threaten to use, any atomic weapon” (42 U.S. Code § 2122). The penalties for a violation of that section are a fine of “not more than $2,000,000” and “a term of imprisonment not less than 25 years or to imprisonment for life”; and if the violation includes using, attempting or conspiring to use, or possessing and threatening to use an atomic weapon, the imprisonment is bumped up to “not less than 30 years” or life; and if the death of another person results from the violation of 42 U.S. Code § 2122, the penalty is imprisonment for life (42 U.S. Code § 2272).
(So…if you kill somebody with nerve gas, you can get the death penalty, but if you kill someone with anthrax or a nuclear weapon, then the maximum penalty is life in prison? Now that’s odd. Although I’m sure there are other terrorism-related charges that would apply if you set off a nuke on American soil, and some of those would put the death penalty on the table.)
I think it’s fairly safe to say that even post-Heller and McDonald, SCOTUS won’t likely be striking down any of these laws anytime soon.