A law that went into effect Thursday aims to curb gun violence after newly released data shows a rise in murders across California in 2020. Homicides were up 31%, and in most cases, the killer used a gun. The rules on who and how often guns can be purchased in California have changed with Senate Bill 61. According to the author, SB 61 has two key provisions. "Right now, if you're under 21, as of today you can no longer purchase these centerfire semi-automatic rifles in California. That's very significant," said Sen. Anthony Portantino, a Democrat from California's 25th District. "The second piece of it is, for the rest of the population, you can only buy one of these a month."Although it was signed into law two years ago, Portantino said the law only goes into effect now because the justice department needed time to create an implementation strategy and ensure accountability for gun dealers by creating a checks and balances system. "Yes, would I have liked it to have gone into effect immediately? Absolutely, because you know the need for sensible gun control frankly now is more important than ever but we didn't need the system to get up and running and so this was the time that we agreed upon," the state senator said. The new law is being implemented on the same day that California Attorney General Rob Bonta released data on gun use in California last year. Firearm use makes up 74.2% of homicides. Portantino believes the new law will work toward reducing the use of firearms for criminal purposes."I definitely think this is going to make Main Street, California more safer. I think it's going to cut down on mass shootings. Basically, it's going to keep these weapons that are designed to kill multiple people in a short period of time out of the hands of those who are most likely to use them," Portantino said. The California Rifle and Pistol Association, who opposed the bill when it was first introduced released this statement:"Fresh statistics released today show California's homicide rate increased by 31% over the past year. That's not from law-abiding gun owners -- that's from bad actors and people Gavin Newsom has released out of jail. Legislators should be focused on crime prevention in this state rather than limiting the way Californians protect themselves."