Generally. In the Post-Finley and post-1367 world, the thoughtful analysis to be applied in federal court, when evaluating subject-matter jurisdiction, should be phrased as follows: A source of subject-matter jurisdiction must be found for each claim, by each party against each defendant. Federal subject-matter jurisdiction may be subdivided into:
(1) Original Subject-Matter jurisdiction, e.g., 28 USC §§ 1332 (Diversity, original subject matter jurisdiction) and 1331 (federal question, original subject-matter jurisdiction) AND
(2) Supplemental Subject Matter jurisdiction, 28 USC § 1367.
Impleader and Compulsory Counter-Claims. The traditional view was that bringing a claim under 13(a) or under Rule 14, generally gave the claiming party a big advantage, because any defects in original subject-matter jurisidiction were saved by ancillary/pendent jurisdiction. However, it would be more analytically accurate to say that the subject-matter jurisdiction of the U.S. District courts is limited and must always be justified. Therefore, a source of original subject matter jurisdiction is usually needed, and, in its abscence, supplemental subject-matter jurisdiction must be available. Generally speaking, in regard to claims brought pursuant to Rule 13(a) and 14(a), provided there is a legitimate anchor claim, as we discussed in relation to the Palmer case, defects in original subject-matter jurisdiction are saved by supplemental subject-matter jurisdiction under 28 USC § 1367. The test under Rule 14(a)[1] for a claim for indemnity or contribution is very narrow, and narrower than any other test under the rules. (See illustration 2). The standard for a Rule 13(a) claim, "same transaction or occurrence" is a narrower test than the "same constitutional case" requirement of 1367(a) (the test for which in Palmer is "each claim involves the same facts, occurrences, witnesses, and evidence"), therefore, if they meet the requirements of 14(a)[1] or 13(a), they will easily meet the requirements of 1367(a).
Joinder of Claims under Rule 18(a). Rule 18(a) would allow the defendant in Illustration 1 above, to join his claims for personal injury and damages against the third-party defendants impleaded for contribution only. To the extent that these claims arise out of the same transaction or occurrence, an assumption under our hypothetical, they would fall under the same constitutional case requirement of section 1367(a). To the extent that claims do not arise out of the same transaction or occurrence, so that they are rule 18(a) claims, BUT are part of the same constitutional case, they may also fall under supplemental jurisdiction of 1367(a). Illustration 2 presents how the different Rule tests relate to each other, as the previous discussion shows, it is possible that some claims that do arise out of the same transaction or occurrence may be joined under Rule 18(a).
Exception. Claims by plaintiff. Even if they meet the requirements of 1367(a), claims by the Plaintiff against someone made a party pursuant to Rule 14(a), even Rule 13(a) compulsory counterclaims, are expressly precluded by 1367(b). A reasonable argument might be made that to preclude compulsory counterclaims is a ridiculous result, but it is a ridiculous result required by the literal language of 1367(b), and, as I mentioned in the highlights, some courts read it the way it is written, not the way it was intended to be written.
Venue. Additionally, a venue objection is not available to the impleaded third parties, as to matters that are within the supplemental jurisidiction of the court. This could include Rule 13(a), Rule 14(a) and certain Rule 18(a) claims. It is also deemed waived when the defendant removes a case to the Federal Court.