Definition
EMP, as used in legal and regulatory contexts, is an abbreviation for electromagnetic pulse — a burst of electromagnetic energy capable of disrupting, damaging, or destroying electronic systems, power grids, and communications infrastructure. The pulse may originate from a nuclear detonation at high altitude, a non-nuclear directed-energy weapon, or a natural solar event (coronal mass ejection). In legal materials, EMP appears primarily in the following contexts:
1. National security and defense law. EMP is addressed in federal executive orders, defense authorization acts, and homeland security directives as a category of threat requiring infrastructure hardening and continuity-of-government planning.
2. Critical infrastructure protection regulation. Federal agencies — principally the Department of Homeland Security, the Department of Energy, and the Federal Energy Regulatory Commission (FERC) — have issued rules and guidance treating EMP as a distinct hazard to the bulk electric system, alongside physical attack and cybersecurity threats.
3. Emergency management and preparedness law. State and federal emergency management frameworks increasingly reference EMP as a named contingency requiring pre-disaster planning, mutual aid agreements, and legislative authorization for executive emergency powers.
4. Insurance and liability contexts. EMP exclusions appear in commercial property and cyber insurance policies. Courts and regulators have begun addressing whether EMP-caused losses fall within war exclusions, act-of-God clauses, or cyber coverage provisions.
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Common Language
Modern common usage (Wiktionary): Initialism of electromagnetic pulse; also, less commonly, initialism of enamel matrix protein.
Historical common usage (Webster's 1913): The abbreviation EMP does not appear in Webster's 1913. The underlying phenomenon was not yet recognized in legal or scientific discourse at that time.
Editorial note: The common meaning and the legal meaning are aligned — EMP in legal materials uniformly refers to electromagnetic pulse. The research challenge is not a gap between common and legal meaning but rather the term's relative novelty in legal sources: most substantive legal treatment post-dates 2000, and the regulatory and statutory record is still developing.
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Common Confusion
EMP is sometimes conflated with cyberattack in regulatory and insurance contexts. The two are distinct: a cyberattack targets software, data, or networked systems through code or unauthorized access; an EMP physically damages or destroys hardware and electronic components regardless of software state. This distinction matters in insurance coverage disputes (some cyber policies exclude physical damage) and in regulatory jurisdiction (cybersecurity standards under NERC CIP do not currently require EMP hardening). Researchers should not assume that EMP preparedness rules and cybersecurity rules occupy the same legal space.
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Why It Matters in Research
Temporal gap in sources. Burrill's Law Dictionary — the primary historical source available here — contains no entry for EMP. The electromagnetic pulse as a weapons or hazard concept entered technical literature only after high-altitude nuclear tests in the 1960s (notably the 1962 Starfish Prime test). Legal and regulatory treatment is almost entirely post-2000. Researchers should not expect historical legal dictionaries to provide definitional or doctrinal support.
Regulatory record is fragmented. EMP-related legal obligations arise from executive orders (including E.O. 13865, signed 2019, on coordinating national resilience to electromagnetic pulses), FERC proceedings, National Defense Authorization Act provisions, and DHS guidance — not from a single codified statutory scheme. Corpus research requires cross-referencing multiple agency records and legislative histories.
Insurance and tort law is emerging. The question of whether EMP-caused losses are covered under existing property, business interruption, or cyber policies is not settled. Researchers working on coverage disputes should track both policy language and the small but growing body of regulatory guidance on EMP as a defined peril.
Jurisdictional variation in emergency management. State legislatures have addressed EMP at different levels of specificity. Some states have enacted standalone EMP preparedness statutes or included EMP as a named hazard in emergency management codes; others have not. State-level corpus research requires checking current statutory codes rather than relying on uniform treatment.
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Historical Dictionary Support
Burrill's Law Dictionary does not contain an entry for EMP. The excerpt provided from Burrill concerns EMENDA — a Latin term for pecuniary compensation in Saxon law — and is unrelated. No other historical legal dictionary in the standard shelf (Black's, Bouvier's, Tomlin's, Jacob's) contains a substantive EMP entry, for the same reason: the phenomenon postdates these sources entirely.
This is a case where the absence of historical dictionary support is itself informative. Researchers should treat EMP as a term of art that has entered legal usage through the regulatory and national security apparatus rather than through common-law development. Its meaning in legal sources derives from scientific and technical usage, not from legal tradition.
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Jurisdictional Note
Federal law provides the primary framework for EMP-related legal obligations, particularly for bulk electric system operators subject to FERC jurisdiction. State-level treatment varies considerably: some states have enacted specific EMP preparedness legislation; others address EMP only indirectly through general emergency management statutes. Researchers working on state-level obligations should verify current statutory codes, as this is an area of active legislative development.
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Encyclopedia Cross-Reference
See Law Mind Encyclopedia: National Security Law; Critical Infrastructure Protection; Emergency Management Law.
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