The constitutional principle derived from the Supremacy Clause is federal preemption. Michael S. Greve focuses on constitutional law and federalism, including federal preemption. Federal preemption applies to state law regarding federally chartered banks. Maine has state preemption of firearms laws. The FECA contains an express preemption clause. North Dakota has state preemption of firearms laws. Montana has state preemption of most firearms laws. Arkansas has state preemption for most firearms laws. These laws are being challenged as a violation of preemption. Nevada is a traditional open carry state with complete state preemption of firearms laws. Riddell's attempt at the same federal labor preemption defense attempted by the NFL failed. California has state preemption for many, but not all, firearms laws. Enabling and disabling of kernel preemption replaced spinlocks on uniprocessor systems. TuxOnIce provides advantages such as support for symmetric multiprocessing and preemption. This new version uses kernel preemption for improved interactivity.