Associated Press, YouTube

54 Colorado's sheriffs are suing to block two gun-control laws scheduled to take effect this summer, later today. The sheriffs are joining other gun-rights activists in trying to block a law limiting the size of ammunition magazines. The sheriffs say they're also suing to block a new law expanding background-check requirements for private gun purchases.

Earlier this year, dozens of county sheriffs tried unsuccessfully to persuade lawmakers not to adopt the gun measures. Gov. John Hickenlooper signed the ammunition limit and background-check bills soon after they were approved by the Legislature. They take effect July 1st.  The Denver Post has more on this story.