Multidistrict litigation is a legal procedure in United States federal courts in which lawsuits involving similar issues (common issues of fact) are consolidated in one court (called the MDL court) for the purpose of convenience and efficiency in pretrial matters, such as discovery. These lawsuits are generally returned to their original federal district courts for trial. Claims that are often the subject of multidistrict litigation are product liability claims against pharmaceutical companies, securities fraud cases, and airplane crashes.

In Washington state, as in all states, multidistrict litigation (MDL) is a federal legal procedure that consolidates multiple lawsuits involving common factual issues to streamline pretrial processes like discovery and motions. This consolidation is for efficiency and convenience and is managed by the Judicial Panel on Multidistrict Litigation (JPML), which decides whether cases should be transferred to an MDL court. While the pretrial proceedings are centralized, each case retains its individuality and, after pretrial matters are resolved, the cases are typically sent back to their original courts for trial. MDLs are common in complex cases such as pharmaceutical product liability, securities fraud, and major accidents like airplane crashes. It's important to note that MDL is a federal mechanism and does not apply to state court proceedings unless a specific state statute or rule provides for a similar state-level consolidation process.