Can same-sex sex committed in (e.g.) western countries be prosecuted in (e.g.) Morocco? Pretty much the title, is same-sex sex also illegal when not committed in a homophobic country when visiting there? E.g. could social media posts put you on trial when you'd visit such countries?
That depends entirely on the laws of the country involved. Some countries do make having homosexual relations a crime, indeed a very serious one. I haven't heard of one which prosecutes for being in a same-sex marriage or relationship entered into in another country, but such a country could hold such a trial if it chose to. Perhaps more likely, if a same-sex couple visited such a country, evidence of a continuing same-sex relationship might be treated as evidence of same-sex sexual acts, and thus of a crime under that country's laws.
"Polyamory" is usually used to refer to having more than one romantic relationship at a time, which is pretty unobjectionable as far as the law is concerned. It might get you into trouble in a divorce proceeding, but the laws that still exist addressing it are largely dead letters. I assume you're asking more about polygamy, or having more than one one spouse at a time. I was surprised to learn that there hasn't been much activity in this area since Obergefell, at least not a lot that has led to development of the arguments you're asking for. The most on-point case I can find is Collier v. Fox, No. CV 15-83-BLG-SPW-TJC, 2018 WL 1247411 (D. Mont. Feb. 22, 2018), where a married couple and another woman sued the state because its criminal and civil laws prohibited the second woman from entering into the marriage. The court tossed the challenge to the criminal prohibition based on the parties' standing, saying that there was not a sufficient threat of criminal prosecution, and it dismissed the challenge to the civil restrictions based on Reynolds v. U.S., 98 U.S. 145 (1878), where the Supreme Court said that each state has the right "to determine whether polygamy or monogamy shall be the law of social life under its dominion." There was no appeal, so the decision was never reviewed. The only other case I've seen directly challenging the laws was Sevier v. Thompson, No. 2:16-CV-659-DN-EJF, 2018 WL 1378803 (D. Utah Jan. 26, 2018), where some anti-gay activists tried to overturn Obergefell by suing to force Utah to let one of them marry a computer and three of them marry each other. If you can't guess how this ends, I'll tell you that it does not end well. The plaintiffs all admitted that they didn't actually want the relief they were asking for, so the court threw the case out on standing. The same dude also tried to intervene in a lawsuit (United States v. North Carolina, No. 1:16CV425, 2016 WL 7335627 (M.D.N.C. Dec. 16, 2016)]) over the North Carolina bathroom bill, saying that a man trying to marry a machine or marry multiple people belonged in the same category as a man trying to marry a man or a man who identifies as a woman. I'm sure you won't be surprised to learn that the court told him to go to hell again. Because these were all tossed at the very early stages, there wasn't much development of the arguments for or against polygamy, though it was clear that everyone was basically talking about an extension of Obergefell's recognition that "the right to marry is a fundamental right inherent in the liberty of the person." There have been several scholarly articles, though, addressing the issue. A few that popped up include: A Yale law professor considering whether plural-marriage bans could survive a challenge based on equal protection rather than due process; A Loyola Marymount professor reviewed several post-Obergefell books considering the future of plural marriage and concludes that (1) Western condemnation of plural marriage is strongly informed by racism and xenophobia, (2) legal reactions against plural marriage may do more to harm the people they are meant to protect, and (3) whatever benefits may accompany plural marriage, banning it does not entail the same kinds of harms as bans on gay marriage; and A William &amp; Mary law student published an article running through the different ways a court might analyze the question and argued that Obergefell should generally permit polygamy, regardless of which test a court applies.
We can start by looking at the text of the law. US federal law 18 USC § 2252A(a)(3)(B) says: Any person who... knowingly... advertises, promotes, presents, distributes, or solicits through the mails, or using any means or facility of interstate or foreign commerce or in or affecting interstate or foreign commerce by any means, including by computer, any material or purported material in a manner that reflects the belief, or that is intended to cause another to believe, that the material or purported material is, or contains— (i) an obscene visual depiction of a minor engaging in sexually explicit conduct; or (ii) a visual depiction of an actual minor engaging in sexually explicit conduct... shall be punished as provided in subsection (b). I'm not sure how much posting the name without the link would protect you, given that you posted it with the explicit intent that someone would go and look at it. On the other hand, your intent was not to "advertise" or "promote" it, and you didn't actually "distribute" the material.
Anti-discrimination laws apply to certain protected classes only. Homelessness (real or assumed) is not one of them, so it is perfectly legal to bar such people from your premises. It is also perfectly legal to bar people with red hair (assuming this is not indirect discrimination against certain racial groups). Nobody is required to serve everybody who comes in; what you are not allowed to do is ban women, homosexuals or other groups set out in the applicable statutes.
Communicable diseases are endemic to the human condition Some places, times and situations are riskier than others but there is always a risk in widespread travel. Outside of disease spread, there are other risks in travel; for example, if no-one traveled at all there would be no motor vehicle deaths. On the flip-side, not traveling has its own dangers; for example, you will not die in a house fire if you are in your car. Of course, there are enormous benefits to widespread travel; economic, cultural and personal - life is to be experienced after all. If you stop the skier from skiing, then you have just damaged the livelihood of all the people who depend on tourism; the airline, the hotel, the bartender, the ski technician, the baker in the ski resort etc. Everything is allowed unless it is prohibited By and large, this is the way that the law works. It's legal to do anything you like. Unless it isn't. It isn't illegal to travel to, say, Finland. So you can. If the government (of whichever country) decides that the costs of allowing people to travel to Finland now outweigh the benefits then they can prohibit it. However, that is a political decision; not a legal one. As for your drink-driving example, I am old enough to remember when it wasn't illegal to drive drunk, although I was too young to drive. Of course, if you are in Somalia or Kenya it's still legal. Also, what counts a drunk varies by country - you can have a couple in Finland but cross over into Russia and you are breaking the law. Why does Finland allow such recklessness? Because it's a political decision and politicians in Finland and Russia have reached different conclusions about what level of risk is acceptable. Same with travel restrictions.
Criminal Code 293 outlaws polygamy and bigamy, and identifies as an offender Every one who (a) practises or enters into or in any manner agrees or consents to practise or enter into (i) any form of polygamy, or (ii) any kind of conjugal union with more than one person at the same time, whether or not it is by law recognized as a binding form of marriage, or (b) celebrates, assists or is a party to a rite, ceremony, contract or consent that purports to sanction a relationship mentioned in subparagraph (a)(i) or (ii) In other words, it is against the law to go through the ceremony with multiple partners, and to "enter into a conjugal union", even if not solemnized in any particular fashion. "Common law marriage" is broadly recognized in Canada (except in Quebec), with specific details governed by the province. This too is a case where people who "act as if" married are treated as actually married, given certain circumstances (which exist in a polygamous marriage). The question of having children is not relevant to the law, indeed having sex is not a requirement for something to be deemed a polygamous marriage, and the law against polygamy also says nor is it necessary on the trial to prove that the persons who are alleged to have entered into the relationship had or intended to have sexual intercourse. In this particular case, we do not know the specific details, but it is reasonable to assume that there was no posturing or faking, and there were multiple solemnization ceremonies, so the polygamy is overt. The claim is that it is constitutionally protected.
Can you unambiguously, legally, and conclusively determine what is and is not a "porn site"? I'm sure many are easy... but what about that "Swimsuit modeling" site, or the "Artistic Nudes" site featuring classic French Renaissance paintings? There will always be a grey area. What makes a "site" in a legal sense? Consider all the blog sites filled with user generated content: If just a few pages out of tens-of-thousands are hardcore, indisputable porn, would you require the entire domain to be classified XXX, even if 99% of its content is completely innocent? Who would enforce this? Are you proposing an "Internet Police" force to review all new domain names and their content before they get approved? That is called "Prior Restraint on Free Speech", and is established law. Suppose a site does get approved, then immediately changes the content of their pages from Cooking Recipes to hard-core porn. Who is going to review and approve every update to every website, when sites are updated constantly?! Maybe you're proposing that any individual who finds porn on a .ORG site has the right to sue for damages? This would likely clog the courts with endless vigilante lawsuits about what content belongs on which domain. This is a flat out horrible, poorly thought out idea.
It is not entrapment because entrapment must be done by officers of the State (police usually). A member of the public inducing another to commit a crime is not entrapment and not a defense to having committed it. Entrapment is a "thing" in Ireland as it is in all common law jurisdictions, however, the specific limits on what police can and cannot do vary by jurisdiction. Police posing as underage children to catch pedophiles is legal throughout Australia (i.e., not entrapment). Police are more restricted in Canada and the USA but I believe that online "trawling" by police is legal in those jurisdictions too, however, they must remain more "passive" than Australian police. Yes, there is a crime being committed, the crime of attempting to engage in underage sex. It doesn't matter that the actual crime attempted is impossible to commit because the "victim" is not actually underage. Evidence is evidence – it doesn't matter who collects it. However, amateurs in the handling of evidence are more likely to botch it up in a way that would allow the defense to have it ruled inadmissible than professionals (although even they can botch it up).