Brandon Garrett, a University of Virginia law professor, testified (in December 2010, in a Texas court) that the rate of exonerations across the (USA) is now averaging more than one a month.
Seven of the 261 national exonerations came from Harris County, Garrett said.
He was giving evidence in a Harris County case where defence lawyers were trying to argue the constitutionality of the death penalty, partly on grounds of the extensive number of people sentenced to death who were later exonerated, some posthumously.