1) The ADA increased the power of federal government because it allows the federal gov. to practice its power nationally on an issue that can intersect with state laws. For example, it protects people with disabilities from discrimination, meaning that marriage can not be prevented from handicapped people, something that is classified as a state law.

Preemption gives the federal government authority over the states by invalidating state laws when they conflict with federal laws.

2) The U.S vs Lopez case decreased federal power by ruling against the federal government, and further limiting certain powers of theirs.

Devolution takes power from the federal government, and gives it to the local governments, therefore narrowing the powers of the national government and increasing those of the state governments.