Here is an interesting question. If an employee of an organization (OrgA) is on a long-term (several years) leave without any pay and benefits and working for another organization (OrgB), and publishes a paper, what affiliation should be mentioned on that paper.
I tried searching on the net and found a whole lot of opinions, but there does not seem to be a consensus on the issue. From reading those views, it seemed to me that the following would be a reasonable algorithm:
1. If either of the two employers have a specific policy on it, follow that. If the policy of the two employers are in conflict, and can not be accommodated simultaneously, ask the legal cell of the two employers to work something out.
2. If the organizations have no official policies on this, then ask the publisher if they have a default policy. If yes, follow that.
3. If publisher too does not have a policy, then what is the convention in your discipline.
4. If there is no strong convention of the discipline, then of course, it is up to the authors.
So how should an author decide.
Some argue that affiliation is primarily to get in touch with the author, and hence the current affiliation should be used. Some argue the same point (about affiliation being primarily a way to get in touch) but they lead to the conclusion the "permanent" affiliation should be used since the contact may happen much later than the time of submitting the article. Of course, in the age of Google Search, it does not seem convincing that affiliation should primarily be a way to get in touch with the authors. Who writes letters these days?
The other set of arguments are based on the credit to the organization for supporting research. So if the work was completely or mostly done when the researcher was at OrgB, then only OrgB affiliation should be used. On the other hand, if the work was mostly done when the researcher was still at OrgA, then OrgA affiliation should be used. And if the two institutions contributed significantly to the research, then show both affiliations. Seems simple, but if support is the primary parameter, then what about the funding agency. It seems to me that Department of Science and Technology should make all it grantees adjunct scientists in DST, and then insist that they write the affiliation of DST in all the papers where DST grant was a significant component of the research support.
I don't have an answer, but I want to raise an issue here. Many universities have started to have a policy that insists that anyone who maintains a lien with them must use their affiliation in all scientific publications. Does it make sense. If someone is on long leave, and the other place is not just providing the salary/benefits, but also the entire research support, why should the previous organization name be listed in affiliation. At best, there can be acknowledgement somewhere that the person continues to maintain its lien with the previous university. (And this is how it used to be.)
What has changed are the rankings of the universities and how rankings are decided. Most rankings would check the number of papers published by the researchers of a university and they of course, check only the formal affiliation and not what is written on a footnote or an acknowledgement. So a university wants to get credit for a paper for which it has made not an iota of contribution. Just because they promise to hire you back when you come back.
To me, it seems very similar to "if you use any facility in my lab, you must put my name as a co-author in any publication, it does not matter if I have made any intellectual contribution to the paper or not." So for a large lab, the lab director may have even one paper per week. This is quite rampant in academia, but the good thing is that most people who are not lab directors dislike the system. And I am hoping that most faculty members would find out their university policy and if indeed it is trying to garner credit for research done elsewhere, they will actively oppose such policies.