Researchers suggest that new, more powerful weapons are part of the reason gunshot wounds are more deadly. Above, a newly assembled AR-15 rifle at Stag Arms in New Britain, Conn.

(AP Photo/File)

City councilors in Boulder gave final approval to a ban Tuesday night on the sale and possession of assault weapons, bump stocks and high-capacity magazines. It was proposed in response to the high school shooting in Parkland, Florida.

The law requires people who own magazines that hold 10 or more rounds or bump stocks to dispose of them or sell them by July 15. People who already own assault weapons will be able to keep them but must get a certificate proving prior ownership.

Councilwoman Mirabai Nagel said she struggled mightily before deciding to vote in favor of the measure.

"We're going to see a lot of court cases coming before us. I think that we're going to spend a lot of time and money. It's not that lives aren't worth that, but I think that there was a better way of going about this," she said.

But councilor Aaron Brocket said he hopes other communities will join Boulder, "and that we will also see more of these bans at the state level and one day, at the federal level, so that these weapons will no longer be present in our society to the extent possible."

The city council is likely to amended the new assault weapons ban in various ways in the coming weeks. During a public comment period before the vote, attorneys for the Mountain States Legal Foundation told councilors they would challenge the ban in court.