What's the proper way to (APA) reference a settlement agreement?
According to the table of contents (pdf) for the APA 6th edition style guide, the APA defers reference styles for legal materials such as court decisions, statutes, legislative materials, and administrative and executive materials to The Bluebook®, which requires a purchase.

However, the APA Style has a blog, which has about 10 posts tagged legal, which gives guidance for a generic Name v. Name court case as follows:


  Name v. Name, Volume Source Page (Court Date)
  e.g.
  Lessard v. Schmidt, 349 F. Supp. 1078 (E.D. Wis. 1972)


And for the in-text citation:


  Name v. Name (Year)
  or
  (Name v. Name, Year)
  e.g.
  Lessard v. Schmidt (1972)
  or
  (Lessard v. Schmidt, 1972)


A settlement is just a specific type of court decision, is it not?