I did some more digging. With how many countries and states/provinces there are, you could easily write a whole book or series of books on this topic. I don't feel like writing books, so this post won't be very thorough.
For the best advice, you should of course see a lawyer. The law changes over time, so some information may be out of date already.
Worldwide Overview
There is a review of suicide laws from around 2015. The authors found 142 out of 192 countries had laws against encouraging or assisting a suicide.[1] The review suggests to me that abetting, accomplicing, advising, aiding, assisting, causing, counseling, encouraging, facilitating, inciting, instigating, leading, procuring, promoting or soliciting a suicide or suicide attempt was illegal in some countries. Suicide pacts (partners?) were also illegal in some countries.[1]
The review doesn't provide much help on which of these laws might apply to an online discussion or guide on suicide methods. Perhaps at least the laws making "advising" or "counseling" illegal could criminalize suicide method discussion. But the other terms used by laws might be stretched to include suicide method discussion as well.
One article claims Australia was the first country to make pro-suicide websites illegal. It did so in 2006.[6]
Australia
The Criminal Code Act 1995 has a Subdivision G which, among other bans, seems to make suicide method instructions illegal to send over a carriage service.[4] A carriage service carries communications using electromagnetic energy,[5] which includes the Internet. So discussing suicide methods over the Internet appears to be illegal in Australia, subject to some conditions. Or at least illegal wherever that law applies in Australia.
One article opines that websites outside of Australia are not usually subject to the penalties of the suicide carriage service law.[6] However, I wouldn't expect Australians using those websites to be immune to those penalties.
Despite the censorship, I can at least praise Australia for making the legal situation clear. I wish the same could be said about other countries.
United States
The situation in the U.S. is a bit confusing. There is some evidence that explaining a suicide method to a particular person can be illegal when resulting in suicide, despite the First Amendment.
A newspaper article in The Atlantic (from 2016) indicates 39 U.S. states had laws against assisted suicide. The article suggests the majority of states don't consider "talking or communicating" to be assisted suicide.[3]
However, J.D. candidate Sweeny suggests that those laws against assisting suicide could apply to some cases involving speech. He says, "It is quite likely that a person who offers material assistance specific to an instance of suicide, such as instructions or advice about how to commit suicide, could be found guilty of assisting suicide under an assisted suicide statute."[7]
He goes on to describe a case where someone provided suicide method advice, stayed during the suicide and cleaned up afterward. That person's organization, Final Exit Network, ended up being guilty of assisting the suicide.[7]
Sweeny also mentions the case of Melchert-Dinkel, who was found guilty of assisting a suicide despite not physically assisting. Sweeny opines that "had Melchert-Dinkel refrained from offering specific advice on how his victims should hang themselves, he may not have been convicted for assisting suicide".[7]
Overall, it's possible, but not clear to me, that most states' assisted suicide laws could be applied to suicide method discussions resulting in suicide.
The Atlantic also lists 7+ states where the law explicitly enables talking or communicating to be illegal, assisted suicide.[3] In these states, discussing methods might be extra risky.
On the other hand, the laws of those 7+ states might not survive court scrutiny unchanged. Minnesota lost the "advise" and "encourage" portions of an assisted suicide statute in a court battle. The decision relied on the First Amendment.[7]
Even without explicit laws against advising someone about suicide, other laws might be stretched to apply. Sweeny presents two cases where defendants were convicted of involuntary manslaughter for the suicides of others. However, in those cases the defendants were "physically present at the scene of the suicide and physically assisted with some aspect of the suicide".[7] That wouldn't be the case for an online discussion of methods. I'm not sure how possible an involuntary manslaughter conviction is.
How common is prosecution for discussion of suicide methods?
- From about 1994 to 2011, there were 6 people sentenced in Minnesota, United States for aiding a suicide.[2] I'm not sure how many cases related to discussing suicide methods.
- One article says Australia made pro-suicide websites illegal in 2006. The authors in 2009 were unaware of any enforcement for the law.[6]
Conclusion
There are many places in the world where discussing suicide methods could be or become illegal. If you want advice for your particular location or situation, see a lawyer.
References
[1]: Mishara, Brian L. and Weisstub, David N., "The legal status of suicide: A global review," International Journal of Law and Psychiatry, vol. 44, pp. 54–74, Jan. 2016.
https://www.sciencedirect.com/science/article/abs/pii/S0160252715001429
[2]: "Ex-nurse to appeal aiding suicides conviction," Washington Post, 16-Mar-2011.
http://www.washingtonpost.com/wp-dyn/content/article/2011/03/15/AR2011031503467.html
[3]: M. Majchrowicz, "The Volunteers Who Help People End Their Own Lives," The Atlantic, 06-Jul-2016. [Online]. Available:
https://www.theatlantic.com/health/...s-who-help-people-end-their-own-lives/489602/. [Accessed: 24-Oct-2019].
[4]: Australian Government, "Criminal Code Act 1995." [Online]. Available:
http://www.legislation.gov.au/Details/C2019C00301/Html/Volume_2. [Accessed: 24-Oct-2019].
[5]: Australian Government, "Telecommunications Act 1997." [Online]. Available:
https://www.legislation.gov.au/Details/C2019C00273/Html/Volume_1,
http://www.legislation.gov.au/Details/C2019C00273. [Accessed: 24-Oct-2019].
[6]: J. Pirkis, L. Neal, A. Dare, R. W. Blood, and D. Studdert, "Legal Bans on Pro-Suicide Web Sites: An Early Retrospective from Australia,"
http://dx.doi.org/10.1521/suli.2009.39.2.190, 15-Jun-2009. [Online]. Available:
https://guilfordjournals.com/doi/abs/10.1521/suli.2009.39.2.190. [Accessed: 23-Oct-2019].
[7]: S. Sweeney, "Deadly Speech: Encouraging Suicide and Problematic Prosecutions," Case W. Res. L. Rev., vol. 67, p. 941, 2017 2016.
https://heinonline.org/HOL/Page?handle=hein.journals/cwrlrv67&id=981&div=&collection=
If you have trouble finding a particular paper, check Sci-Hub. Another option is doing a Google Scholar search for the title and clicking the PDF link on the right or the "All X Versions" link.