The National Association for the Advancement of Colored People is locked in a standoff with the Internal Revenue Service, preferring to risk its tax exemption rather than hand over documents for an I.R.S. review that the civil rights group contends is politically motivated. While it is rare for an organization to defy the I.R.S. openly, the N.A.A.C.P. is not the only group that believes it is being made a government target for its positions on issues. Roughly a dozen nonprofit organizations have publicly contended that government agencies and Congressional offices have used reviews, audits, investigations, law enforcement actions and the...