Co-authors on a study have cut communication, what can be done?
Ultimately, you can't make someone collaborate or communicate with you if they don't want to. I think your only option is to either abandon the project, or rewrite it to remove the parts that your collaborator contributed and then publish it as solo work. I don't see how union representation could help in any way.
I'm pretty surprised that this would happen twice, and would wonder if there's something about your interactions that might be causing it. People usually don't voluntarily drop all contact with a collaborator unless something has happened that makes them uncomfortable to continue working with them - ethical concerns, abusive behavior, severe inability to communicate, etc. If you have a colleague who works in the field, and you trust them to be honest with you, you might want to show them the history of your communications and see if they observe any red flags which you might not be aware of.
If you have any common acquaintances with this collaborator, they might also be able to give you some idea as to what is going on.
Normally I'd wonder if there is some involuntary reason for lack of communication - illness, personal problems, death, spam filters - but here it sounds like you've ruled those out.
Regardless of what initially caused the breakdown, I don't think your strategy of "weekly emails/calls for a year" was a good one. I would probably send a maximum of about three messages / calls, with longer periods in between each, and the last one being an ultimatum of sorts: "if I don't hear back from you by date X, then I am going to do Y" (where Y could be stopping work on the project, or removing their contributions and proceeding, or whatever). And then if they don't respond, you do Y, and move on with your life. Persistence can be a virtue, but in this case I'm reminded of the saying about how insanity is when you keep doing the same thing and expect different results.
Another tip for the future is to have multiple projects going on with multiple different collaborators, so that if one of them falls apart (either for scientific or interpersonal reasons) you still have some publications.
I've seen this many times.
Some scientists, in particular senior scientists, can be outrageously busy. They might have to be on your co-author list because they are responsible for the data. They might insist on being in the loop for the data analysis, but when it's time for feedback on exactly that, they have no time. They may be completely drowning in emails. They might rarely pick up the phone because they're constantly travelling or in meetings. They certainly don't have time to read a paper draft related to some data they provided to someone junior months or even years ago; they may not even remember. Do not take it personally just because they're not communicable. I've found that some scientists are eager to take on a lot more work than they are able to do (because everything is awesome!), but underestimate the time it takes. See Hanlon's razor and Hofstadter's law. Scientists are human, the expectation from a senior scientist may not be human, the result is what we observe. I've had situations where I thought a senior scientist had lost interest, but then spoke to him for 5 minutes at a conference and soon found out that he was still quite interested instead — just incapable of allocating time.
Some senior scientists are very good at time management, manage to reply to emails and even give detailed manuscript feedback even when they're no less busy than any other senior scientist. In my experience, they are a minority.
How to prevent this? If possible, seek out less senior co-authors. That will reduce the risk of this happening. I've had better responses from co-authors junior enough to desperately need papers to have a chance at graduating/staying in science/etc.
How to get out of this situation? Try to reach them in other ways: phone their office, phone or email a secretary to find out when the scientist may be in, or if you're lucky enough to both attend a conference any time soon, try to seek them out during a conference break. Prepare some clear questions: do they still want to be on the paper? Are they happy for publication to go ahead? In my experience, the result is usually one of either:
- Please go ahead and remove me as a co-author, I don't have time. I'm OK with the data being only acknowledged/cited, instead of full co-authorship.
- Please go ahead, keeping me as a co-author. If other co-author X approves the draft, you can assume I'm fine with the draft as well.
- Let me introduce my postdoc/PhD student who is happy to take over my role on this study (we will both be co-authors).
- I will have time in X days/weeks/months, please wait for me then.
I've seen all of the above, sometimes with an added apology. I would be very cautious of the last answer, because in my experience, it usually ends up being not true.
If you reach them and they say they don't have time, you could even suggest if they might have a PhD student or postdoc who they could introduce you to (see point 3). Personally, I think #3 is the most professional answer.
You may need to press them, or ask a senior colleague to press them, to get one of those answers at all.
Asssuming as always that we get a complete and accurate picture of the situation by the OP:
Until physics or medicine do something that under today's standards is indistinguishable from magic, there is one individual natural resource that depletes non-stop: time.
And yes, you are a grown up and you take your chances and accept risks when collaborating, like the ones you saw materialized. But that should not mean "if it doesn't work out smoothly, well, let it die".
The upshot is that I have 3 years worth of research that I can't publish without his consent.
Compare: We are equal partners and decision-makers in a company, and you go on and disappear. Does this mean the company is doomed to remain in limbo forever? Dragging my fortunes with it?
I would seek both legal and academic-ethics advise on this, and on your current situation, probably they are available in your institution for free? Seek detailed expert advise on how you could go on and publish. And in the advice that you will receive, try to detect the most "peaceful" approaches and suggestions -the goal is not to attack or criticize or shame the partner-that-disappeared, just not to throw your time and work in the garbage bin.
And, for the long-run, plan also some work that you can do alone.