What legal precedents guide federal use of nonlethal munitions and chemical irritants against protesters?
Executive summary
Federal use of chemical irritants and so-called nonlethal munitions against protesters is governed by constitutional limits—primarily the First Amendment’s protection of speech and assembly and the Fourth Amendment’s guard against unreasonable seizures and excessive force—and by developing federal and appellate case law that applies those principles to crowd control tactics [1] [2]. Recent district-court injunctions and circuit rulings have narrowed when agents may deploy pepper spray, tear gas, or projectiles, but those orders are contested on appeal and the law remains in flux [3] [4].
1. Constitutional guardrails: First and Fourth Amendment standards
Courts frame the legality of force against demonstrators as a clash between the First Amendment right to petition, assemble and observe government actions and the Fourth Amendment’s prohibition on unreasonable seizures and excessive force; judges have enjoined tactics they view as retaliation for protected speech or as seizures of peaceful observers without reasonable suspicion [1] [3]. Legal scholars and litigation repeatedly characterize chemical agents—OC, CS, CN and similar irritants—as force that can constitute a seizure or excessive force when used indiscriminately, giving rise to Fourth Amendment claims especially after the Supreme Court’s expansion of “seizure” doctrine in Torres v. Madrid [2] [5].
2. Recent district-court precedent: Menendez’s Minnesota injunction
U.S. District Judge Katherine Menendez issued a preliminary injunction barring federal officers deployed to Minnesota from using pepper spray or other nonlethal munitions against people engaging in peaceful, nonobstructive protest activity and from detaining drivers without reasonable articulable suspicion, finding plaintiffs likely to succeed on First and Fourth Amendment claims [1] [3]. The order specifically described instances where chemical irritants were used against observers of ICE operations and concluded some deployments were retaliatory rather than necessary for law enforcement safety [6] [3].
3. Appellate pushback and procedural posture
That Minnesota injunction was temporarily stayed by an appeals court while the government pursues review, illustrating how district rulings restricting force can be short-lived pending appellate intervention and showing that precedent is not settled nationwide [7] [4]. The appeals stay underscores the tension between courts trying to protect constitutional rights at the preliminary stage and federal agencies asserting operational and safety prerogatives [4].
4. Circuit-level and local precedents shaping practice
Circuit rulings and federal injunctions outside Minnesota have similarly constrained less-lethal tactics: for example, a D.C. Circuit decision in litigation challenging MPD use of chemical irritants and explosive munitions has produced precedential rulings affecting how courts view governmental seizures and property issues in protest contexts [8], and a Ninth Circuit ruling has been cited in challenges to police use of launchers and projectiles at protests, influencing a federal judge’s ban on some LAPD “less-lethal” weapons [9].
5. Statutory and policy overlays at the state and local level
State laws and municipal policies also shape permissible uses; California’s AB 48, for example, forbids deploying chemical agents or less-lethal projectiles against peaceful protesters and requires use only in response to violence or objectively dangerous situations, with strict prohibitions on aiming at head, neck or vital organs [10]. Those statutory constraints can provide additional bases for litigation and injunctions when federal or local agencies operate within such jurisdictions [10].
6. Practical legal tests courts apply and competing government arguments
Courts typically assess whether force was retaliatory (impermissible suppression of speech), whether officers had reasonable suspicion or probable cause to detain, and whether the force used was excessive or necessary under the circumstances; defendants (including DHS) counter that such tools are legitimate crowd-control measures to protect officers and the public and warn that broad judicial limits could endanger safety during violent unrest [1] [7] [4]. Reporting shows government statements defending deployments even as judges find uncontroverted evidence of improper use in some cases [6] [3].
7. Where precedent leaves open questions
While Torres and recent circuit/district rulings give plaintiffs pathways to Fourth Amendment claims and courts are increasingly willing to issue injunctions against use of chemical irritants and projectiles, the appellate process, divergent circuit decisions, and varying state statutes mean national legal standards are still evolving and not definitively settled by the Supreme Court in this context [2] [4] [8].