There is a state law on the books in Nevada that forbids it.
http://www.breitbart.com/big-government/2015/03/06/couple-denied-foster-kids-because-they-carry-guns-for-self-defense/
Brian and Valerie Wilson of Nevada want to take in foster kids and start a family but are being prohibited from doing so because they carry guns for self-defense.
On March 5, they testified in front of the Assembly Judiciary Committee in favor of a bill that would change state law and allow them to foster—and eventually adopt—but they face strong opposition from the state Division of Child and Family Services deputy administrator Jill Marano.
According to Las Vegas Review-Journal, the Wilsons testified in favor of Assembly Bill 167, which “would allow Nevadans with concealed carry permits, and law enforcement officers, to carry loaded guns on their person in a home or car and still be eligible to be foster parents.”
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