The proposals for the big EU calls like Horizon 2020 contain detailed work packages and plans for how the research effort is going to be orchestrated to be successful. To my knowledge, the quality of this planning is a decisive factor in the acceptance of a proposal.

If a research partner drops out halfway through the project, the whole effort may fall apart - and with research institutions and industrial partners booking the alloted funds each month, such a failure is hard to justify for any EU officer.

Of course, it is ridiculous to simply require that the UK partners be dropped from the project without a significant change of plan or adequate substitution.

Edit: Also, the aim of these projects is always to strengthen industry or scientific progress in the participating countries - so politically, if the UK really drops out this would be giving something for free to a competitor.

I'm having trouble seeing why UK partners here are specifically going to drop out of a funded research project simply because Brexit.

They may struggle to recruit staff needed for the positions, or even lose existing staff¹. For

Successful projects often lead to future projects, so people thinking of projects in a few years time might not want to start collaboration in the UK, at least if there's an alternative elsewhere in the EU.

¹ For example, the UK lost me — after the 2014 European Parliament elections in the UK, where UKIP won most votes, I started looking for a job elsewhere.

I don't think so. It's just about the uncertainty. In many frameworks you need partner institutions from three or more EU countries. If you can replace a UK institution from one form another country, you can get certainty back and potentially greatly simplify future administration. That unfortunately makes a lot of sense.

As far as I understand it, nobody is immediately removing UK investigators from existing, already awarded projects. Those are going on as planned (I'm part of one myself). I'm not sure it would even be possible to do so under the research programme's rules. What's happening is that people who are just now putting together new groups of investigators in order to send an application into the next funding call are thinking twice about including UK partners in their applications, because it seems like a potential risk to the project.

In general a partner dropping out of a project partway through is very disruptive, so you like to avoid it. You want partners who will still be there for at least 4 years from now: 1 year for the application preparation/review, plus 3 years for the project if the application is successful. Many people are not sure if that will be true of UK partners; can you say, today, that the UK will still be part of the EU funding mechanisms through 2020? I think there's a good chance they will be, even if they leave the EU (they will probably end up joining the research framework a la carte, like Norway, Iceland, and Switzerland have). But I could forgive people for considering it a risk they'd rather avoid.

I am still having trouble seeing, for certain and without ambiguity, that Brext itself implies that UK researchers can't be listed on future projects. is that a straight-line, 100% implication? Everything I've read about Brexit suggests that nobody can predict the specifics about what will happen, when it will happen, or how much will actually happen.

You're correct, basically nobody knows what will happen. That's why many people don't want a UK partner in current applications (or at least prefer a different partner if a suitable one can be found), because they don't want this risk that, in 2 or 3 years, the UK partner might have to withdraw, if the UK leaves the EU research programmes. They might not have to withdraw, too, but nobody knows for sure, so it's a risk. Hopefully by next funding round the UK's intentions/timeline will be clearer, so people will either unambiguously know that the UK will stay in the EU research programme long-term, or that it won't.

Thanks for clarifying that this is just risk estimation based on not knowing what the outcome is. There is also a risk in not including UK institutions- they have some mighty fine researchers there, so not including them might lead to a project not being approved (for lack of continental experts in a specific topic) or being unsuccessful (for lack of execution capabilities).

It's trading a well-understood risk for a one that is not well-understood, hence my comment about it being irrational.

Since when were people rational? The PR effects alone are reason to break ties with the UK, similar to the situation with Panama after the Panama Papers. I'm already asking international vendors to setup corporate entities in an EU country instead to keep business as usual. When discussing this only from an EU negotiation perspective I think you're missing the psychological impact Brexit has had on us Europeans (Yes I understand many Brits still consider UK a part of Europe but so does Russia so...). If they want to leave, let them leave. It's over. Good luck, have fun.

Science funding is extremely competitive. Why would it be rational for EU researchers to take on additional risk?

What additional risk is there? Be specific.