In Spokeo v. Robbins, the Court notes that the Constitution requires a concrete injury even in the context of a statutory violation." It infers from that claim that "Robbins could not allege a bare procedural violation divorced from any concrete harm" to satisfy the concreteness requirement.
Procedural laws are best understood in contrast with substantive laws.Substantive law defines rights and duties. Procedural laws specify the rules and procedures under which those rights and duties are enforced.
Robbins sued under a statute, the Fair Credit Reporting Act, which regulates the collection and use of consumer credit reports. Under the act, Robbins has a right to fair and accurate reporting, and the act gives him a right to sue civilly for violations.