WeekendPizzaiolo

Short visits (2-4 weeks) should be easier, and they should be even easier if you plan to engage in tourism exclusively.

I think it goes both ways. As a recovering academic myself, I have given talks at German universities. One time, while having lunch after a talk, I was told that upgrading to a formal scholar position would require a German D-visa. Point well-taken. The CBP officer looks at the totality of facts and evidence to make the determination of a person's intent. I used to hold a UK research scholar visa but then I moved back to the US. Twice while visiting the UK for short personal trips, I told the officer that I had no interest in staying in the UK, and yet I was questioned in secondary. The officers wanted evidence of ties to the US. After leaving the UK on the day promised on multiple trips, I no longer experience extensive questioning at the UK border.

You don't necessarily need sponsorship from a university. Even small organizations and companies can sponsor a J-1 visa through a Department of State-approved organization, such as the American Immigration Council (AIC). I have used AIC in the past to sponsor interns. AIC provides the required health insurance for a fee. The visa process through them was straightforward. 1. https://www.americanimmigrationcouncil.org/exchange-visitor. 2. https://exchange.americanimmigrationcouncil.org/exchange-visitor/research-scholar

As others have mentioned, Independent Research is listed as a valid purpose for an ESTA according to the Department of State [1], it must be "Independent research, no salary/income from a US based source, or benefit to US institution." I would interpret the last part broadly that you would not be able to collaborate nor have any US co-authors on papers that result from the research. If you wanted to engage in collaboration, you would need to consider a J-1 visa, but they are typically longer than 72 days, and you could not be outside the US for longer than 30 days during the J-1 program without invalidating the visa, and you would be subject to the two-year rule upon the J-1 program's conclusion [2]. Given that the US is not in your long term plans, the last part probably isn't an issue for you. [1] https://travel.state.gov/content/dam/visas/BusinessVisa.pdf [2] https://www.uscis.gov/policy-manual/volume-2-part-d-chapter-3

Possibly. The authors of the law may have tried to memorialize the constitutional basis for Respect for Marriage Act and chose Article IV's Full Faith and Credit clause: It was written 238 years ago. It does not explicitly mention foreign records. As I understand it, the common law doctrine of comity is typically applied by the government when considering foreign judgements and records. I could not find any mention of comity in the Respect for Marriage Act. I do not know why they did not include it, but it probably require a bit more text to cover edge cases. For most modern countries, including Columbia, this is probably pretty cut and dry. However, a blanket recognition of any foreign record might be precarious. Some countries with substandard human rights laws may allow for marriages that would be illegal in any state of the US. I am not disagreeing with you here. Having lived in EU and US, there generally is greater regulatory alignment between European countries since so many countries are next to each other. In my experience, it is not just the US, however. Large, isolated countries (US, Brazil, China) tend to integrate less and follow their own norms. For example, Brazil does not recognize trusts in their law at all. Living trusts are convenient because you can avoid the years and processing costs of probate - loved ones are able to pay for property tax, electricity, and groceries immediately. Brazil has no notion of trusts having any kind of entity status like a foreign corporation or person. Moreover, non-Brazilian wills are not completely enforced in Brazil. Brazil can prevent you from leaving someone out or prevent you from giving your Brazilian assets to charity as can be done in the US and UK. Each country has a different sociopolitical history that led to following different norms. I suppose this is why it is difficult to write a law that recognizes documents from 193 countries. I guess this is why multilateral treaties and international standards are helpful for improving trade, economic, and social cooperation.

Where did you find the ~3.4 percent statistic? Thanks.