DPTrombly has a post suggesting that, inasmuch as European states will be willing and able to enforce the Responsibility to Protect only within a defined geographic area, R2P will come to resemble a European Monroe Doctrine, with Europe attempting to ensure certain norms of behavior by states within its sphere of influence, i.e., "Sahara, Sahel, Mediterranean rim, and Balkans."
Does the analogy work? I'm not convinced. The U.S., as DPT indicates, relied on Britain's naval power to enforce the Monroe Doctrine for most of the 19th century. And not too long after the U.S. became capable of using its own navy to enforce the Monroe Doctrine, Theodore Roosevelt proclaimed in 1904 his famous 'corollary' to the Doctrine which "declared that misgovernment (or 'chronic wrongdoing')" by Latin American governments would be grounds for U.S. armed intervention (Penguin Dictionary of International Relations, 1998, p.337). Applying this principle via his paternalistic pronouncement that "we must teach the Latin Americans to select the right man," Woodrow Wilson sent the Marines into Mexico in 1914 (ibid., p.573).
By contrast, R2P is less paternalistic than the Monroe Doctrine as applied by TR and Woodrow Wilson. R2P's application is limited to four circumstances: genocide, war crimes, ethnic cleansing, and crimes against humanity (see M.W. Doyle, "International Ethics and the Responsibility to Protect," Int'l Studies Review 13:1, March 2011). It is not a question of teaching the inhabitants of country X "to select the right man [or woman]." A leader can drive his or her country into the ground and can be as corrupt as all get-out, but as long as he or she does not engage (or very credibly, by his or her own pronouncement, appear to be right on the verge of engaging) in genocide, war crimes, ethnic cleansing or crimes against humanity -- all of which, with the possible exception of ethnic cleansing, have accepted definitions in international law -- the question of R2P does not even arise.
Of course, application of R2P will be selective and considerations of the sort mentioned by DPT will influence the 'selections'. But that does not mean that R2P will be used to legitimize interventions of the kind that Wilson ordered in Mexico. Thus "European Monroe Doctrine" may not be the right description, inasmuch as it may conjure up a history of paternalistic, imperialistic interventions that I think few have any interest in defending or repeating.