Acknowledge grants (which may indicate conflict of interest) in double blind review? I have run into a bit of a double-bind for double-blind reviews as an editor. In short, the problem comes down to if reviewers should see an author's Acknowledgements section which cites the grants that supported the work. Either way has problems:


If you let the authors acknowledge their grant during the review process, it is often trivial to find out who is involved in authoring the paper (since the awardees for many grants are published online).
On the converse, if you do not let authors acknowledge funding sources, it is not possible for reviewers to identify potential conflicts of interest or biases in the manuscript.


In general, at least in my core topics, conflicts of interest due to funding is rare, so I am leaning strongly toward having such funding sources omitted. However, I could see it being a significant problem for other disciplines that I collaborate with. Does anyone know of any good rules of thumb, other than "use your judgement, case by case"?

Note: My general stance has been "No Acknowledgements during review" up to this point. However, on considering the issue in light of allowing reviewers to be aware of funding sources, there seem like very rational reasons why you should have this information available to reviewers, provided it could be done without identifying the authors or unfairly biasing the reviewers.
I think the best approach is, as recommended in the comments, to cite the funding organization but not the particular grant.  In fact, I have recently encountered some journals that request this information explicitly as part of the submission meta-data, which I think is very wise.

Citing only the funding organization may, indeed, be extremely vague information: for example, "US National Science Foundation" tells you pretty much nothing.  In general, however, this is already enough information to determine potential conflicts of interest:


If the funder is a broad-mission government agency, there there is generally no meaningful conflict of interest to consider.
When funding comes from a private organization, such as a company or a foundation, that information is generally enough to identify potential conflicts of interest.  It doesn't matter which division of an oil or pharmaceutical company is funding a project---all of their research projects will still be expected to relate to their bottom line somehow.