Updated at 4:25 p.m. ET

A federal judge in Missouri has ruled that the state's ban on same-sex marriage violates the equal protection clause of the U.S. Constitution, adding to an already confusing mix of contradictory decisions that is sure to propel the issue to the Supreme Court.

The decision by U.S. District Judge Ortrie Smith in Kansas City upholds a Circuit Court's ruling on Wednesday. It comes a day after the 6th Circuit Court of Appeals in Cincinnati, Ohio, upheld voter-approved bans on gay marriage in Michigan, Ohio, Kentucky and Tennessee. In Michigan, a lower court had struck down the ban in March.

Citing the same 14th Amendment "equal protection" argument used in the most recent ruling, federal courts including those in Pennsylvania and Virginia have also struck down same-sex marriage bans.

Thirty-two states now have legal same-sex marriage, while 18 others ban the practice.

[An earlier version of this story incorrectly stated that the 10th Amendment to the U.S. Constitution contains the "equal protection" clause. It should have said the 14th Amendment.]

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