tyranny of the minority
What distinguishes a democracy from mob rule? A couple of things, but chief among them is the legal protection of individual rights. You can't hang all the redheads just because the majority wills it. Redheads have as much of a right to life as their brown-haired fellow citizens - not more, not less.
The cracks start showing when the concept of individual rights morphs into particular protections for particular factions. This is a grave mistake: the inevitable result is that individual members of the protected minority begin to conceive of themselves, if not already the case, as a distinct political entity or faction within the broader polity. Because equivalent protections are not granted to non-minorities, a feeling of resentment stemming from rightly perceived unequal legal status is bound to emerge. Anyone who grew up with a sibling who received "special treatment" as a youngster can sympathize.
Majorities succumbing to demagoguery and becoming tyrannical are tragically well documented in practice. The usual causal explanation is the absence or insufficient protection of individual rights. But the converse possibility of minoritarian tyrannies is rarely addressed in liberal political theory. What happens when no single faction comprises more than half of the voting public, i.e., the polity becomes "majority-minority"? Either factions unite to form a majoritarian coalition, or a dog fight (a.k.a civil war) ensues from which one faction emerges victorious and imposes its will on all the others using its special legal protections as cover to legitimate its rule.
Whether political distinctions are enumerated on the basis of immutable descriptors (race, sex) or mutable ones (class, profession), the resulting factionalization is inevitably destructive of the common good. Individual rights must never be distorted to protect collective factions; doing so negates their entire purpose and can result in minoritarian tyranny.