Background
Enbridge sought approval from the Michigan Public Service Commission to replace the two existing Line 5 pipelines at the Straits of Mackinac with a new 30-inch pipeline housed in a concrete-lined tunnel beneath the lakebed. The project would decommission the existing dual pipelines but would not change Line 5’s carrying capacity or service.
Indian Tribes and environmental organizations intervened to oppose the project. The PSC approved it under 1929 PA 16 after concluding that the project satisfied that statute and the Michigan Environmental Protection Act. In its MEPA analysis, the PSC generally limited its review to the replacement segment and tunnel, although it considered greenhouse-gas emissions associated with consuming products transported through Line 5. It declined to consider the common-law public trust doctrine. The Court of Appeals affirmed, and the opponents appealed.
The Court’s Holding
The Michigan Supreme Court held that courts must review an agency’s application of MEPA de novo. MEPA requires the decision-maker to identify environmental harms factually and proximately caused by the conduct at issue, fairly compare the environmental impacts of the proposed conduct and its alternatives, and separately consider potential harm to public trust resources.
Applying that framework, the Court held that the PSC should have determined whether constructing the replacement project would factually and proximately extend Line 5’s operating life and thereby cause additional environmental harm. The PSC also used inconsistent scopes when comparing the project with alternatives and failed to determine whether the project would pollute, impair, or destroy public trust resources, including Great Lakes waters and submerged lands and the public’s rights to fish, hunt, travel through, and otherwise use them. The Court reversed the Court of Appeals, vacated the PSC’s approval order, and remanded for further proceedings.
Key Takeaways
- Judicial review of an agency’s MEPA determination is de novo, without deference to the agency’s application of MEPA.
- MEPA reaches environmental harms beyond the immediate project only when factual and proximate causation connect those harms to the conduct under review.
- An alternatives analysis must compare environmental impacts using a consistent benchmark and permit a reasoned choice among the proposed conduct and alternatives.
- MEPA requires separate consideration of potential harm to public trust resources under the common-law public trust doctrine.
Why It Matters
The decision requires the PSC to reconsider Enbridge’s tunnel proposal under a broader and more structured MEPA analysis before the project may receive approval. On remand, the agency must address whether the project would extend Line 5’s lifespan and cause attendant environmental harms, compare alternatives consistently, and expressly assess effects on public trust resources.
More broadly, the ruling establishes that Michigan courts independently review agency applications of MEPA and clarifies that causation, consistent alternatives analysis, and public trust impacts are distinct components of environmental review.