In an exhaustive legal opinion released on Monday's Martin Luther King Jr. Day holiday, Attorney General Ken Paxton criticized decades-old and long-moot guidance issued by John Cornyn, his opponent in the March 3 Republican primary for U.S. Senate, and claimed a litany of Texas initiatives meant to offset historical discrimination against people of color and women are unconstitutional. Legal experts quickly pushed back on Paxton's claim in a press release that the opinion is binding, arguing that the attorney general cannot unilaterally overturn state laws by declaring them unconstitutional. And Cornyn, the state's senior U.S. senator who served as state attorney general from 1999 to 2002, bashed the 74-page opinion, accusing Paxton of using the Office of the Attorney General as a political weapon in their closely watched GOP primary contest. "Was this bogus 'opinion' an illegal, in-kind contribution to his campaign? Inquiring minds (and the Federal Election Commission) want to k…