Facebook Inc. is facing backlash over a report that it allowed advertisers to exclude certain ethnicities from seeing ads. But it is unlikely to face litigation, even though some civil rights lawyers say the advertising tool enables unlawful discrimination.

Last week, ProPublica reported that Facebook’s advertising portal allows ad-purchasers to target or exclude certain “ethnic affinities,” which include “African-American,” “Asian-American” and “Hispanic.” As ProPublica noted, the ad tool could be used to block minorities from seeing postings about available housing or employment opportunities.