Governments interfering with churches since they have tax exemptions and/or tax benefits In most Western nations( especially with a large Christian population), there are usually tax-exemptions for churches and/or some kind of tax-deductible benefits for those who donate to churches. However, based on the Western law system (especially Anglo-Saxon legal systems), would there be a way for governments to argue that they can start interfering with church policies and/or church practices, rituals, etc.? For example, could governments start arguing that churches have to accept same-sex marriages, therefore, ensuring that same-sex marriages take place during church ceremonies, and so on so forth?
I'm just going to talk about the US. The First Amendment to the US Constitution codifies that Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof;... What is clearly prohibited by this Amendment would be Congress (or any inferior legislature via the 14th Amendment) restricting the ability of religions which refuse to marry same-sex couples from marrying opposite-sex couples, or in general outlawing any kind of religious law about who a particular church is willing to marry (e.g. only marrying if both parties are of the religion). However, legislatures are generally allowed to influence action via government inducements (I'll just use inducements to describe subsidies, tax breaks, etc). The current precedent for determining whether a particular legislative action violates the Establishment Clause is the "Lemon Test," from Lemon v. Kurtzman, which has the following test: Government action violates the Establishment Clause unless it: Has a significant secular (i.e., non-religious) purpose, Does not have the primary effect of advancing or inhibiting religion, and Does not foster excessive entanglement between government and religion. On the first point, I think the law fails - inducing religious establishments to perform same-sex marriage does not have a "significant secular purpose" because ultimately the government doesn't care whether or not you have a marriage ceremony, just that you sign a marriage certificate with an appropriate witness, which can be a government official. The law could survive on the second point if it could be shown to have at least the preponderance of being for social good, if it is argued that the law's purpose is to make church marriage ceremonies more accessible for same-sex couples by inducing more churches to perform them, and not to harm churches that don't perform them. However, this would probably be an uphill battle, since the law has the practical effect of promoting some religions' beliefs over others. The law probably fails on the third point as well, going back to the previous point that it effectively results in the government choosing one religious practice to promote over another. However, the Lemon Test often criticized or entirely disregarded by the current Supreme Court, for example in the case American Legion v American Humanist Association (a case decided by the current Supreme Court): This pattern is a testament to the Lemon test's shortcomings. As Establishment Clause cases involving a great array of laws and practices came to the Court, it became more and more apparent that the Lemon test could not resolve them. It could not "explain the Establishment Clause's tolerance, for example, of the prayers that open legislative meetings, . . . certain references to, and invocations of, the Deity in the public words of public officials; the public references to God on coins, decrees, and buildings; or the attention paid to the religious objectives of certain holidays, including Thanksgiving. Even without the Lemon Test, we can look at Walz v. Tax Commission of New York for an idea of when tax breaks for religious establishments is allowed (emphasis mine): The legislative purpose of the property tax exemption is neither the advancement nor the inhibition of religion... New York, in common with the other States, has determined that certain entities that exist in a harmonious relationship to the community at large, and that foster its "moral or mental improvement," should not be inhibited in their activities by property taxation or the hazard of loss of those properties for nonpayment of taxes. It has not singled out one particular church or religious group or even churches as such;... The State has an affirmative policy that considers these groups as beneficial and stabilizing influences in community life and finds this classification useful, desirable, and in the public interest. This paragraph seems to provide some argument both ways. First, the bolded section would seem to prohibit using government inducements to promote one religious practice over another, and that the government can only assist religious institutions when the assistance is applied equally. On the other hand, states are allowed to grant tax relief to religious organizations "that foster..."moral or mental improvement,"..." A legislature could argue that the law promotes "moral improvement" by encouraging acceptance of same-sex marriage, rather than a particular religious belief. However, I don't think that such an argument would prevail over the general prohibition on promoting any religious exercise over another. Government assistance for religious organizations is very thinly held to be permissible only when it is equal. In my opinion, the Supreme Court already has to use twisted gymnastics to argue in favor of any government assistance of religious organizations granted because of their religious status, so they are unlikely to allow something this far (especially since it is usually the conservative justices arguing in favor of these policies, and they are less likely to do same-sex marriage any favors). On the other hand, a permissible policy may be to have government grants for any organization that performs same-sex marriage ceremonies, whether or not that organization is religious. Whether or not that is allowed is likely going to depend on what proportion of the receiving organizations are religious in nature, but there may be enough hotels and other non-religious venues that would qualify that such a law might survive.
Constitution of the USA, Article IV, Section 1: Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof. and the Commerce Clause (Article I, Section 8, clause 3): [The Congress shall have Power] To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes; SCOTUS has found the former to mean that states that do not allow same-sex marriages in their laws must recognize same-sex marriages registered by other states - Obergefell v. Hodges. Maybe one could argue that driver licenses are not equivalent among states, but I would expect judges (SCOTUS) to require a very well reasoned explanation. For example, maybe Alaska could refuse to recognize licenses from Florida because Florida drivers do not know how to cope with snowed roads. But even in that case Alaska probably would need to produce data showing that these measures aim to serve the public interest (avoid accidents) and that there are no other ways of getting the same result. OTOH the Commerce Clause has been successfully used to avoid states mandating racial segregation of travellers, so it is quite reasonable to see it being used to prevent a state from trying to limit the mobility of citizens from other states (again, in the supposition that the state restricting it cannot show a compelling reason to do so). AFAIK, only the Federal Government could invoke the Commerce Clause; I would expect a lot more people (in your example, the PA government or maybe even any PA driver) would have standing.
There are only a few areas of law of which I am aware that U.S. law treats people who are engaged to be married differently (although perhaps with more thought I could expand the list). Fiance(e)s come under a special immigration status when applying for a visa. There is a body of law related to whether an engagement ring is an absolute gift or is conditional upon being married (this is not uniform from state to state and I don't recall what the majority rule in those cases is under the common law). In South Carolina, ownership disputes over engagement rings are litigated as breach of promise to marry actions. Pre-marital agreements governing a future marriage can be made by people who are engaged (although a post-nuptial agreement is also equal in effect in most cases). People who are engaged, like spouses, are generally considered to be in a "confidential relationship" with each other which imposes higher duties with respect to fairness in their dealings with each other than strangers, but generally less high duties than fiduciaries. While not strictly arising from the status of being engaged, adult cohabitants are generally agents for service of process of each other at their shared home, and are often considered to have a legally significant relationship for purposes of domestic violence statutes (usually related to either domestic violence crimes or temporary restraining orders). I am not familiar enough with the law of France to fully answer the balance of the question, which someone more familiar with that law can expand upon. But, there is similarly a special immigration status in French law for a fiance(e). And, French law, in a flourish so romantic it could scarcely be any other country's law, also allows people who are engaged a right to marry after one of them has died in certain circumstances: "The legislation that allows posthumous marriages stems back to when a dam burst in 1959 and killed 420 people in southern France." It was most recently invoked in 2014 when a grieving French woman was granted permission by the French President to marry her former fiancé, who tragically died in 2012, just a month before they were due to wed. To be eligible the bride to be had "to convince the President of France that her’s was a special case and that her love for Michael went beyond the grave. It took four letters to the president and 20 months of waiting, desperately hoping for a positive response." The President's discretion in this matter is somewhat similar to the pardon power in U.S. law. This French law was also invoked in 2009. The law in question is set forth at Articles 171 of the French Civil Code. In English translation this states: Article 171 The President of the Republic may, for serious reasons, authorize the celebration of the marriage if one of the future spouses is dead providing a sufficient gathering of facts establishes unequivocally his consent. In this case, the effects of the marriage date back to the day preceding that of the death of the spouse. However, this marriage does not carry with it any right of intestate succession to the benefit of the surviving spouse and no matrimonial regime is considered to have existed between the spouses. I am aware of one documented case where a court entered a post-humous marriage in the United States between people who were engaged, but I am not familiar with any legal authority actually authorizing that action.
The details depend on the state, of course. The common law thing you are looking for is a writ of mandamus -- a court order to a public official to do something (or not do something) that they are required to do under the law. Writs of mandamus were traditionally only applicable to ministerial tasks (i.e. things that are basically paper-shuffling where there is little to no discretion); marriage licenses are typically considered ministerial. With discretionary actions, things are much more complicated because the government official is supposed to have significant ability to decide what should and shouldn't be allowed; mandamus doesn't apply unless there's a right to the action requested. In some cases, mandamus has been replaced with other forms of judicial review, but in Alabama it is definitely still mandamus that's involved (source: mandamus is what's previously been used to stop issuance of licenses). For federal review, which is more likely to get somewhere, the approach to use is the exact same thing that led to DeBoer (the case bundled into Obergefell that was about granting licenses), and Perry, and many of the other gay marriage cases: a lawsuit seeking an injunction or declaratory relief under 42 USC 1983, which allows actions in law and equity whenever anyone denies civil rights to a US citizen (or someone in the jurisdiction of the US) under color of law. The ultimate result of this kind of suit is a federal court order to issue a marriage license, or a declaration that it's illegal to not issue the license (and so anyone who doesn't will be subject to a court order). Violating this order, like any court order, is contempt of court.
In the U.S.: To my knowledge all states and jurisdictions that with a "sales tax" technically have a "use" tax, which means the tax liability falls on the purchaser. However, they require "businesses" (whose exact definition varies by jurisdiction) to collect and remit that tax on behalf of "consumers" (which can also vary, e.g., to exclude businesses that resell). Historically consumers have avoided paying use taxes by purchasing from out-of-state businesses that are not subject to their home states' laws on withholding the use tax: while technically a violation of the tax law neither consumers nor states have had an interest in calculating or auditing use taxes owed, except in the case of very large and unusual transactions. There is a large effort underway by states and "brick-and-mortar" stores that lose business to this virtual "mail order tax exemption" to subject out-of-state businesses to the requirement of collecting use taxes on behalf of the state. A few online businesses (notably Amazon) have acquiesced to this demand. To answer your question: In the U.S., an individual who is not making a "business" of selling items or services is generally exempt from the requirement to collect sales tax. It is the purchaser who has the legal obligation to declare and pay tax on such transactions. But purchasers rarely do.
The First Amendment states Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances. It thus protects such videos. An analogous situation is that there is network news coverage of riots, bank robberies, terrorist attacks and assaults. Backpage was seized because it facilitated prostitution, not just reported or even encouraged it. That is basically where the line exists.
There is no federal prohibition against sexual discrimination in public accomodations. Colorado has an applicable state law, which covers "any place of business engaged in any sales to the public", where "It is a discriminatory practice and unlawful ...to refuse, withhold from, or deny to an individual or a group, because of ...sexual orientation...the full and equal enjoyment of the goods...". No provision exempts lemonade stands. Churches etc. are specifically exempted: "'Place of public accommodation' shall not include a church, synagogue, mosque, or other place that is principally used for religious purposes". Sex discrimination is allowed "if such restriction has a bona fide relationship to the goods, services, facilities, privileges, advantages, or accommodations of such place of public accommodation", an argument that can't reasonably be made in the described case. It is also not obvious that running a lemonade stand is a business (the courts will not admit unsubstantiated Wiki assertions as evidence). It would be relevant to wonder what constitutes a "business" under Colorado law. E.g. is a business license required? In Colorado (US) law, it has not been definitively decided whether there can be a religious exception to the anti-discrimination law. Masterpiece Cakeshop was decided without answering that (the state showed clear religious intolerance in its handling of the case). We do not know how a similar case will be decided: Arlene's Flowers was handed back to the state court with the instruction "do it again" (with nothing more than a mention of Masterpiece Cakeshop). The court cannot establish certain beliefs and practices as "valid religions" (Establishment Clause); the proxy expression that is used is "deeply held belief", which includes atheism. The relationship of the issue to the First Amendment is uncertain.
In general, a seller may make different and inconsistent sales terms with different customers on whatever basis the seller chooses. In some jurisdictions, for some kinds of transactions, specific laws may regulate this. They may require similar treatment, or advertised prices, or whatever. I do not know of any such laws governing the sale of oil, but there might be some. This will depend on the exact jurisdiction (country, state/province, and perhaps city or other locality). Please edit the question to specify the jurisdiction if you want a more specific answer. Price discrimination on the basis of membership in a protected class under anti-discrimination laws, such as race or religion under US federal laws, would be illegal. Proving that the basis was unlawful might be hard, however.