The collection of taxes is an important power delegated to state and national powers. Taxes are collected in various ways, such as tax on certain food and other products. State and national authorities must enforce and pass laws. If one organ of the system does not enforce the law, the other will. Much like the legalization of marijuana, this is a controversial topic but it is a very important example in today's events. Since some states in the United States of America have already legalized marijuana, national powers can ignore state laws and take federal action against those who violate national law. The creation of courts is an essential concurrent jurisdiction that is necessary at both the state and national level. Just as highways are necessary for the people and national powers. Highways are also designed to be convenient for both parties and to ensure the well-being of the population. For example, the drinking age used to be 18 and states suddenly raised the drinking age to 21. This accommodation was made to protect young children who drive while intoxicated and to reduce the rate of fatalities on highways. Of course, the national powers had made some kind of agreement with the state powers so that the funds remained available. This specific mandate is called the unfunded mandate, one of Congress's strategies for influencing state policies (Barbour and Wright, 87-88). Although the powers are said to be competing, there are still gaps in what the national government expects of the state.