The Hawai'i Supreme Court in a 5-0 ruling Thursday said the Hawaii Superferry should conduct an environmental assessment. An environmental impact statement, or EIS, and an environmental assessment, or EA, are different.

An EIS is a document that describes a proposed project in detail and considers its effects on the environment. It can review a broad array of potential effects, including cultural, recreational and economic ones in addition to impacts on the natural environment, including soil, water, air and living species. It also considers alternatives to the proposed activities.

An EIS involves extensive consultation with the community, whose concerns are included in the document. An EIS can be ordered under either the National Environmental Policy Act or the Hawai'i Environmental Policy Act.

An EA is generally a shorter and less-thorough document. If an EA concludes that a project's cumulative impact on the environment will be significant, that can trigger the requirement for an EIS. An EA can also help guide an agency's or project's compliance with the National Environmental Policy Act in situations in which an EIS is not done.