hair-splitting 
adjective
Characterized by or fond of small and overfine distinctions: the legal experts have a particularly hair-splitting mentality...
- How can the Supreme Court possibly know what the most divisive policy is with respect to these hair-splitting distinctions.
- A good example of this is the often hair-splitting legal distinctions between valid and invalid transfers.
- Then they became immersed in hair-splitting debates about difficult ‘moral’ decisions but within a context where everything was justified if politically useful.
Synonyms
quibbling, fault-finding, niggling, cavilling, carping, captious, critical, criticizing, disapproving, censorious, judgemental, overcritical, hypercritical, pedantic, punctilious, pettifogging;
Scottish & Irish pass-remarkable
informal nitpicking, pernickety, picky
North American informal persnickety
archaic nice, overnice
noun [mass noun]
The action of making small and overfine distinctions; quibbling.The aim of these fine distinctions, not to say hair-splitting, is to deny the Marxist thesis that the driving forces of the war were rooted in economic and geopolitical conflicts of the major capitalist powers....
- Avoid complicated issues of public policy; the people need to have their hearts lifted by statements of steely resolve, and there's little time for wonky hair-splitting.
- Even the most intelligent and well-intentioned judge can create a mess by indulging in hair-splitting that, at least on its own narrow terms, may seem reasonable.
Derivatives
hair-splitter
- Human consciousness is too important to be left to the hair-splitters.
- They are the most preposterous and unjustified of all the guesses which can be made about the universe, and I am not enough of a hair-splitter to pretend that I don't regard them as arrant and negligible moonshine.
- However, don't go endlessly back and forth between suppliers in an attempt to grind out a rock-bottom price, otherwise you'll be marked down as a time waster and a hair-splitter.