Covello relied on the U.S. Supreme Court's 2008 Heller decision, which found a local law banning handgun ownership in the District of Columbia to be an unconstitutional infringement of the Second Amendment. The Supreme Court concluded that the Second Amendment protects ownership of guns, such as handguns, that are "in common use," meaning that they are widely owned and legally used for purposes such as personal protection.
The Connecticut plaintiffs argued that assault weapons are commonly used, in the state and across the country, for hunting, sporting competitions and home protection. Common usage makes the weapons and widely owned large capacity magazines subject to Second Amendment protection, the plaintiffs argued.
The state, in its defense of the law, disputed the claim of widespread usage. Referring to Sandy Hook, it argued that the banned weapons and magazines present unjustifiable threats and that gun violence will decrease if both are outlawed.