Dershowitz said Americans who want even-handed gun policy should not leave the arguments up to gun advocates such as the National Rifle Association and Jones without speaking up themselves.
The prosecution also alleges the defendant handed Mr Duggan the gun in a shoebox, 12 to 15 minutes before he was shot and that the box bore the fingerprints of Mr Duggan, Mr Hutchinson-Foster and his girlfriend Desire Cox.
But champions of gun control were handed a defeat when on Tuesday, in Illinois, the Seventh Circuit Court of Appeals ruled that the state's ban on carrying a weapon in public is unconstitutional.