What is the Cooley doctrine?	States and federal government have concurrent power to regulate commerce, unless pre-empted expressly by Congress, or implicitly where Congress has established a comprehensive federal regulatory scheme or where the subject requires uniformity of national laws then regulation goes to the state.
What is the doctrine of selected exclusiveness?	Defines state authority to regulate commerce: 1) States may regulate purely intrastate commerce; 2) Congress may regulate interstate commerce and thereby preempts contrary state laws; 3) federal authority is exclusive over those elements of commerce that are national in scope or require uniform regulation; and 4) states may regulate interstate commerce that is not national in scope, does not require uniform regulation and has not been regulated by Congress.
What is the dormant (negative) Commerce Clause?	A principle that the Constitution's positive grant of power to Congress to regulate interstate commerce carries with it a negative command that the states, without congressional approval, may not discriminate against interstate commerce or unreasonably burden it.
What did the Supreme Court hold in Wabash, St. Louis & Pacific Railway Co. v. Illinois (1886)?	The Court held that Illinois had violated the Commerce Clause by placing a direct burden on interstate commerce in the form of setting rates railroads could charge their customers. Under the Commerce Clause only Congress had the power to do so and states could only place indirect burdens on commerce.

What are police powers?	The general authority of a government to regulate for the health, safety, morals, and general welfare of the people, subject to constitutional limitations. The states possess such general police powers, but the federal government is restricted to the powers that have been given to it by the U.S. Constitution.
What was the original package doctrine?	Chief Justice Marshall's answer, as stated in Brown v Maryland (1827), to the question of when an imported article loses its status as an import and becomes a part of general goods subject to state taxation. According to Marshall, an imported article continues to be an import as long as it remains the property of the importer, is located in the importer's warehouse, and is not taken out of its original packaging. The doctrine was abandoned in 1976.
What did the Supreme Court hold in Cooley v. Board of Wardens (1852)?	The Court held that a Pennsylvania law requiring all ships entering or leaving Philadelphia to hire a local pilot did not violate the Commerce Clause of the Constitution. The Commerce Clause does not deprive the States of power to regulate pilots. Although Congress had legislated on this subject, its legislation manifested an intention to leave shipping regulation to the several states until Congress could pass federal regulations.
What did the Supreme Court hold in Southern Pacific Company v. Arizona (1945)?	The Court found that the Arizona's Train Limit Law imposed an unconstitutional burden on interstate commerce. The Train Limit Law of 1912 made it illegal for any person or corporation to use the state railroad train that has more than fourteen passenger cars or seventy freight cars.

What did the Supreme Court hold in Hunt v. Washington State Apple Advertising Commission (1977)?	The Court struck down a North Carolina law prohibiting the sale of apples in closed containers marked with any apple grade other than USDA grades. The Court found that North Carolina's law violated the Commerce Clause by needlessly discriminating against Washington state apple producers while working to the advantage of local North Carolina apple growers.
What did the Supreme Court hold in Maine v. Taylor (1986)?	The Court held that there was an exception to the "virtually per se invalidity" of discriminatory state legislation under the dormant commerce clause. The Court found that a Maine law prohibiting the importation of out-of-state bait fish was constitutional because Maine authorities couldn't be certain that imported fish would be free of "parasites and non-native species" that might pose environmental harm to local ecology.
What did the Supreme Court hold in Granholm v. Heald (2005)?	The Court ruled that laws in New York and Michigan that permitted in-state wineries to ship wine directly to consumers, but prohibited out-of-state wineries from doing the same, were unconstitutional. These state laws discriminated against out-of-state merchants and violated the dormant Commerce Clause and are not authorized by the Twenty First Amendment.
What did the Supreme Court hold in Michelin Tire Corp. v. Wages (1976)?	The Court upholds a local ad valorem tax on business inventory maintained in its original packaging. The local tax does not violate the Import-Export Clause; it does not discriminate against imported goods. The Court abandons the original package doctrine.

What did the Supreme Court hold in Complete Auto Transit v. Brady (1977)?	The Court upheld Mississippi's tax on transportation companies doing business in the state. Although the state imposed a tax on part of interstate commerce occurring in the states, the tax was permissible under a four-part test: substantial nexus, non-discrimination, fair apportionment, and fair relationship to services provided by state.
What did the Supreme Court hold in Quill Corp. v. North Dakota (1992)?	The Court struck down a North Dakota law that required out-of-state retailers to collect use taxes when they sold goods to North Dakota customers. A state may not impose tax obligations on out-of-state retailers without a physical presence in the state consistent with the dormant Commerce Clause.
What did the Supreme Court hold in Oregon Waste Systems v. Department of Environmental Quality of the State of Oregon (1994)?	The Court held that Oregon's cost-based surcharge on the disposal of out-of-state waste violated the dormant commerce clause. The surcharge discriminates against out-of-state businesses.
What did the Supreme Court hold in South Dakota v. Wayfair (2018)?	State government may tax sales made to their residents by out-of-state sellers, even if the seller does not have a physical presence in the taxing state, overturning its 1992 decision in Quill Corp. v. North Dakota. This means a state can impose a sales tax on online retailers who operate from another state.