So by your definition the Nuremberg Laws of '35 justified antisemitism in Germany, or the Apartheid legislation justified the racial discrimination and the dominance by white people over people of other races in South-Africa?
Just because a democratic majority thinks so and/or a government says so (by law) doesn't make everything right.
MURDER = MURDER:
In 2012, Texas executed Marvin Wilson, a convicted murderer who had undergone five IQ tests that determined his IQ was 61. The only psychological expert to express an opinion at his trial said he was intellectually disabled. Wilson read at around a five-year-old’s reading level and sucked his thumb into adulthood. The Supreme Court declined to issue a stay.
Two years prior, Texas tried to execute Daniel Plata, another intellectually disabled inmate, but Plata’s life was spared after a state district judge found problems with the evaluation methods psychologist George Denkowski used to determine Plata’s intellectual ability. Judge Mark Kent Ellis noted that “it is not generally accepted practice within the field of psychological assessment to obtain an IQ score, declare it invalid, and then estimate an IQ score with numbers,” as Denkowski had done, meaning the psychologist used his own, non-standard questions and estimations to calculate Plata’s IQ.