Final answer:
Horizontal federalism refers to the full faith and credit clause, privileges and immunities clause, and competitive federalism, emphasizing the inter-state relationships and how they must respect each others' laws and judicial rulings, treat non-residents fairly, and sometimes compete in policy-making.
Step-by-step explanation:
The clauses associated with horizontal federalism include the full faith and credit clause, the privileges and immunities clause, and the concept of competitive federalism. The full faith and credit clause, found in Article IV, Section 1, of the Constitution, requires states to accept the court decisions, public acts, and contracts of other states. The privileges and immunities clause, located in Article IV, Section 2, prevents states from discriminating against citizens of other states, ensuring equal access to basic rights such as court protections and property rights. Competitive federalism describes the dynamic where states may compete to attract business, potentially leading to a race to the bottom in terms of regulation and worker benefits.
In the context of fiscal federalism, federal resources are used to influence states through mechanisms such as block grants, categorical grants, and mandates. These financial tools can shape state policies and compliance with federal laws. The intricate interplay of powers and clauses in the Constitution forms the backbone of federal-state relationships and thus affects the scope of federalism in the United States.