By declining to hear the case the Supreme Court has essentially given the “thumbs up” to this law and signaled to other cities that they may do the same.

From Yahoo News:

By declining to hear an appeal filed by gun owners and the National Rifle Association, the court left intact a March 2014 ruling by the San Francisco-based 9th U.S. Circuit Court of Appeals that upheld the measure.

The regulation, issued in 2007, states that anyone who keeps a handgun at home must either store it in a locked container or disable it with a trigger lock.