## Facts

- Walter McNaughton sued Merck & Co., Inc., alleging he suffered injuries after taking the prescription drug Vioxx.
- McNaughton’s theory included allegations that Merck failed to provide adequate warnings about Vioxx’s risks.
- After filing the complaint, McNaughton moved for leave to amend under Federal Rule of Civil Procedure 15 to add 64 additional plaintiffs.
- McNaughton argued the additional plaintiffs could proceed together because each proposed plaintiff took Vioxx, each allegedly received improper warnings about its risks, and each allegedly suffered serious health consequences.
- The motion did not claim that the proposed plaintiffs’ experiences were similar as to source or time (for example, the same prescribing events, exposure periods, or other connecting circumstances).
- Merck objected to the proposed amendment.

## Issues

1. Whether the court should grant leave to amend under Rule 15 to add 64 new plaintiffs when their claims do not arise out of the same transaction, occurrence, or series of transactions or occurrences as required for permissive joinder under Rule 20.

## Decision

- The court denied McNaughton’s motion for leave to amend to add 64 additional plaintiffs.
- The court concluded that, although the proposed plaintiffs shared some common themes (use of the same drug and similar warning allegations), the motion failed to show the type of factual connection required by Rule 20’s “same transaction or occurrence” requirement.
- Because the proposed joinder was improper, the amendment was treated as futile and leave to amend was denied.

## Legal Principles

- Rule 15 directs courts to freely grant leave to amend when justice so requires, but leave may be denied for reasons including futility.
- An amendment is futile when the proposed pleading would not withstand dismissal or would be subject to procedural defects that defeat the requested change, including misjoinder of parties.
- Rule 20 permits multiple plaintiffs to join in one action only if (1) their claims arise out of the same transaction, occurrence, or series of transactions or occurrences, and (2) there is at least one common question of law or fact.
- Allegations that multiple plaintiffs used the same product and advance similar failure-to-warn theories can supply common questions, but common questions alone do not satisfy Rule 20 without a sufficient factual link tying the claims to the same transaction(s) or occurrence(s).
- When a motion to add parties does not allege similarity as to source or time connecting the proposed plaintiffs’ injuries, a court may find that Rule 20’s transactional requirement is not met and deny amendment.

## Conclusion

In *McNaughton v. Merck & Co., Inc.*, the court refused to allow a plaintiff to convert an individual Vioxx action into a 65-plaintiff case through amendment because the motion did not allege a shared set of connected events linking the proposed plaintiffs’ claims as Rule 20 requires; with joinder improper, the court denied leave to amend under Rule 15 as futile.


McNaughton v. Merck & Co., Inc., 2004 U.S. Dist. LEXIS 30287 (2004)