Definition
Arizona is one of the fifty states of the United States of America, admitted to the Union on February 14, 1912, as the forty-eighth state. It is located in the southwestern United States, bordered by California, Nevada, Utah, Colorado, New Mexico, and the Mexican states of Sonora and Baja California. Its capital is Phoenix. As a state, Arizona is a sovereign jurisdiction within the federal system, possessing its own constitution, legislature, judiciary, and body of statutory and common law. In legal research, "Arizona" most commonly appears as a jurisdictional designator identifying the source, applicability, or venue of a legal instrument, decision, or authority.
Common Language
Modern common usage (Wiktionary): A state in the southwestern United States, established 1912, with its capital at Phoenix. Also used informally to refer to the University of Arizona, and historically to the Confederate and U.S. territorial governments of the same name.
Historical common usage (Webster's 1913): Webster's 1913 would have recorded Arizona as a U.S. territory approaching statehood, not yet admitted to the Union at the time of that edition's publication.
The gap between common and legal meaning here is primarily historical rather than semantic. In legal sources predating 1912, "Arizona" refers to a federal territory governed under congressional authority, not a state — a distinction that materially affects the legal weight and character of any instrument or decision issued thereunder. A researcher encountering "Arizona" in a document from the territorial period should not assume the full attributes of statehood apply.
Recognized Forms
/SUBTYPES
Arizona Territory (1863–1912): The federally administered territory organized by Congress in 1863, carved from the western portion of New Mexico Territory. Territorial courts, statutes, and legal instruments from this period operate under a distinct legal regime from post-statehood Arizona law.
State of Arizona (1912–present): The sovereign state admitted to the Union February 14, 1912. Possesses a state constitution, a three-branch government, and an independent judiciary including the Arizona Supreme Court and Court of Appeals.
Why It Matters in Research
The principal research trap with Arizona is the territorial/state boundary. Legal materials from before February 14, 1912 — including court decisions, land grants, contracts, and statutes — were issued under territorial authority, not state sovereignty. Territorial courts lacked the constitutional standing of Article III courts; their decisions and the legal rules they applied may differ substantially from post-statehood Arizona law.
Researchers working in property law, water rights, mining law, or land title chains will encounter this boundary repeatedly. Arizona's water law in particular — built around the doctrine of prior appropriation — developed substantially during the territorial period, and understanding the continuity (or discontinuity) between territorial and state-era rules is essential.
A second research consideration: Arizona is the origin of Miranda v. Arizona, 384 U.S. 966 (1966), one of the most cited cases in American constitutional law. In any corpus search, "Arizona" will appear with exceptional frequency in criminal procedure materials entirely unrelated to Arizona-specific law. Researchers should use jurisdictional filters carefully to distinguish Arizona-as-party from Arizona-as-jurisdiction.
Confederate Arizona Territory (1862–1865) appears in some historical legal documents but had no recognized legal standing under United States law. Instruments purportedly issued under Confederate Arizona authority are of historical interest only and carry no legal effect in any U.S. court or land record chain.
Anderson's Dictionary of Law's cross-reference to TERRITORY points researchers toward the governing legal framework for the pre-statehood period — a useful redirect that acknowledges the complexity without elaborating it.
Historical Dictionary Support
Bouvier's Law Dictionary provides a brief but useful entry acknowledging Arizona's 1912 admission and sketching the Spanish colonial and military history of the region from 1526 forward. The entry is incomplete as published — the text breaks off mid-sentence — suggesting the entry was either abridged in the edition consulted or suffered a printing truncation. What survives confirms the statehood date and the Spanish colonial origin of settlement, including the establishment of a military post at Tucson in 1580. This historical background is relevant to researchers examining Spanish land grants, which survived into the American territorial period and generated substantial litigation over title validity.
Anderson's Dictionary of Law dispenses with independent treatment entirely, directing the reader to TERRITORY. This reflects the dictionary's apparent publication date, when Arizona had not yet achieved statehood or had only recently done so, making territorial status the legally operative category. The cross-reference is methodologically sound: the legal character of Arizona in the period most relevant to Anderson's publication was defined by federal territorial law, not state sovereignty.
Neither dictionary addresses Arizona's state constitutional law, its distinctive water law doctrines, or its later significance in federal constitutional jurisprudence — gaps that are unsurprising given their publication dates but essential for researchers to recognize.
Jurisdictional Note
Arizona operates under the prior appropriation doctrine for water rights, distinguishing it from eastern riparian-rights states. This has generated a substantial body of Arizona-specific water law with limited cross-jurisdictional precedential value. Researchers working in western water law should treat Arizona authorities as part of a coherent regional framework alongside Colorado, Nevada, and Utah, but should not assume uniform doctrine across those states.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Territories and Territorial Governance; Statehood and Admission to the Union; Prior Appropriation Doctrine.