When scientific evidence enters the courtroom, unique challenges emerge. Nowhere is this more evident than in plastics litigation, where courts in the United States increasingly find themselves arbitrating complex scientific questions about chemistry, toxicology, and environmental fate. Our analysis of 67 recent plastics-related legal cases tracked through the Plastics Litigation Tracker (Plastics Litigation Tracker, 2025) reveals a judicial system straining to evaluate scientific claims that often outpace regulatory frameworks and scientific consensus.

Science in the Courtroom: A Fundamental Tension

Legal systems and scientific inquiry operate on fundamentally different principles. Courts seek definitive answers on liability within defined timeframes, while science embraces uncertainty and evolves continuously. This tension becomes particularly acute in plastics litigation, where cases often hinge on emerging science around three key issues:

  • Exposure and possible health effects
  • Recyclability and environmental degradation
  • Chemical leaching and safety

The Microplastics Challenge

Microplastics allegations appear in 12 cases (18%) in our dataset, highlighting their emerging role in plastics litigation. These cases present unique evidentiary challenges:

The Scientific Context

  • Microplastics are typically defined as plastic particles smaller than 5mm
  • Detection methodologies vary widely, complicating comparison across studies
  • Exposure pathways include ingestion, inhalation, and dermal contact
  • Health effects research remains preliminary, with debate about causation and thresholds

The Legal Challenge

Courts must make binary determinations about liability while the science continues to evolve. This creates a fundamental disconnect between the state of scientific knowledge and the legal standard for proof.

Case Development Update: The challenges of microplastics litigation are exemplified by recent case developments. Miller et al. v. Handi-Craft Company Inc., No. 4:24-cv-03782 (N.D. Cal. filed 2024), involved allegations that plastic baby bottles and sippy cups marketed as “BPA-free” nevertheless leached harmful microplastics when heated. However, this case was voluntarily dismissed by plaintiffs in May 2025 (Miller et al. v. Handi-Craft Company Inc., 2025), illustrating how the evolving nature of microplastics science can impact litigation strategies. Key scientific questions that emerged in this case included:

  • What level of microplastic release occurs under normal use conditions?
  • What constitutes a “dangerous” level of microplastic exposure for infants?
  • How should courts weigh evidence of potential harm against scientific uncertainty?

The case highlighted how consumer-facing claims like “BPA-free” can create liability when they address only one chemical concern while potentially overlooking others. The voluntary dismissal suggests the ongoing difficulty in establishing clear causation and liability standards in this emerging area of science.

Recycling Claims: When Aspirations Meet Reality

Recycling-related claims appear in 25 cases (37%) in our dataset, revealing substantial disagreement about what constitutes meaningful recyclability.

The Scientific Context

  • Technical recyclability differs from practical recyclability
  • Regional infrastructure variations create inconsistent recycling outcomes
  • Contamination rates significantly impact actual recycling rates
  • Life cycle assessments reveal complex environmental tradeoffs

The Legal Challenge

Courts must determine what constitutes “false” or “misleading” recycling claims when the truth involves complex technical and systemic factors. Is a product “recyclable” if the technology exists but practical infrastructure doesn’t? What disclosure standard should apply?

Case Spotlight: Rodriguez v. Exxon Mobil (2024)

In this class action, Rodriguez et al. v. Exxon Mobil Corporation et al., No. 4:24-cv-00803 (W.D. Mo. filed 2024), plaintiffs allege that petroleum companies misled consumers by promoting recycling while knowing that most plastic is not practically recyclable. The case turns on scientific questions about:

  • The technical feasibility of recycling various plastic types
  • The economic viability of recycling systems
  • Corporate knowledge of recycling limitations
  • The environmental impact of recycling versus alternatives

Courts must now evaluate whether statements that are technically accurate (e.g., “this product is recyclable”) can nevertheless be misleading when practical constraints prevent widespread recycling.

Health Impact Claims: Causation Challenges

Health impact allegations appear in 18 cases (27%) in our dataset, raising difficult questions about chemical exposure and causation—a significant increase from earlier litigation patterns that reflects growing scientific attention to plastic-related health concerns.

The Scientific Context

  • Plastics contain various additives including phthalates, flame retardants, and stabilizers
  • Low-dose effects and endocrine disruption follow non-linear patterns
  • Exposure pathways are complex and often cumulative
  • Individual susceptibility varies significantly

The Legal Challenge

Courts typically require clear causation chains, which are particularly difficult to establish for chemicals with subtle, long-term, or synergistic effects. How should courts handle cases where the scientific evidence suggests potential harm but cannot definitively prove causation?

Scientific Complexity in Health Claims

Several cases in our dataset involve state and local governments suing chemical manufacturers over alleged environmental contamination and public health impacts. These cases typically face scientific challenges regarding:

  • Background levels of chemicals in the environment
  • Contribution of specific manufacturers to overall exposure
  • Establishment of causation for specific health outcomes
  • Appropriate remediation standards

These challenges often exceed the technical expertise available to courts, creating pressure for alternative dispute resolution mechanisms or regulatory approaches.

The Daubert Dilemma: Gatekeeping Scientific Evidence

Under the Daubert standard, federal judges serve as “gatekeepers” for scientific evidence, evaluating its reliability and relevance. Our analysis reveals that Daubert challenges occur frequently in plastics litigation, with courts often reaching inconsistent conclusions about similar evidence.

The key scientific evidence challenges include:

  • Methodology validation (particularly for emerging detection techniques)
  • Extrapolation from laboratory to real-world conditions
  • Animal studies and their applicability to human health
  • Epidemiological evidence and confounding factors

The Role of Industry Science

Our analysis reveals an important trend: in 41 cases (61%), courts faced competing scientific claims from industry and academic or government sources. This raises critical questions about how courts should evaluate evidence when:

  • Industry possesses unique data about product formulations
  • Academic research faces funding constraints for comprehensive testing
  • Regulators rely partially on industry-supplied data
  • Publication bias may affect the scientific literature

Beyond Individual Cases: Systemic Implications

The scientific challenges in plastics litigation reveal deeper questions about how our society evaluates risk, allocates responsibility, and balances innovation against precaution. Courts are increasingly asked to resolve scientific questions that might be better addressed through other institutions.

As litigation accelerates, these scientific challenges will only grow more acute. Courts will continue to face difficult determinations about emerging science, and outcomes will likely remain inconsistent until more standardized approaches emerge.

In the next article of our series, we’ll explore the economic implications of plastics litigation, examining how legal uncertainty affects markets, innovation, and the transition toward more sustainable materials.

This is the second installment in a four-part series examining the current landscape of plastics litigation in America. The Center for Truth in Science is committed to promoting evidence-based solutions to complex challenges at the intersection of science, justice, and the economy.

Join us for Part 3 of our series: Economic Ripples: How Plastics Litigation Impacts Markets and Innovation.

References

Miller et al. v. Handi-Craft Company Inc., No. 4:24-cv-03782 (N.D. Cal. filed 2024).
Miller et al. v. Handi-Craft Company Inc., Notice of Voluntary Dismissal, No. 4:24-cv-03782 (N.D. Cal. May 20, 2025).
Plastics Litigation Tracker. (2025). State Impact Center. https://plasticslitigationtracker.org/ (accessed May 2025).
Rodriguez et al. v. Exxon Mobil Corporation et al., No. 4:24-cv-00803 (W.D. Mo. filed 2024).