At a Glance: Idaho, Nevada, Hawaii Gay Marriage

Judges have been striking down gay marriage bans at a rapid rate since a landmark U.S. Supreme Court ruling last year invalidated the core of a federal law that defined marriage as only between a man and a woman for determining federal benefits.

Three more state bans are at issue Monday when the 9th U.S. Circuit Court of Appeals considers the marriage laws of Idaho, Nevada and Hawaii. A total of 19 states - including Hawaii - and Washington D.C. now allow gay marriages.

Here are legal issues in the three cases on appeal:

IDAHO: Four same-sex couples filed a lawsuit to overturn the state's gay marriage ban in 2013. A federal district judge struck down the ban earlier this year. Gov. C.L. "Butch" Otter appealed to the 9th Circuit. Same-sex marriages have been placed on hold until an appellate decision.

NEVADA: Eight same-sex couples sued to overturn that state's gay marriage ban in 2012. A federal judge upheld the ban the next year, and the gay couples appealed to the 9th Circuit. Nevada's governor dropped his opposition to the lawsuit earlier this year when the 9th Circuit ruled that gays are a "protected class" like minorities and women. The governor said that ruling, which said the removal of a potential juror because of his sexual orientation was unconstitutional, swung the case in favor of the same-sex couples.

HAWAII: Two same-sex couples sued to overturn Hawaii's ban on marriage. When a federal judge upheld the ban, they appealed to the 9th Circuit. Meantime, Hawaii's state lawmakers made same-sex marriage legal. The question before the 9th Circuit Monday is whether to dismiss the case as moot because gay marriage has been legalized. Gay marriage foes want the appeal to continue in hopes the U.S. Supreme Court someday issues a ruling against gay marriage.

This story is part of our special report: "Gay Marriage". Want to read more? Here's the full list.