Federal Rule of Civil Procedure 42(a) provides that, when two or more separate cases raise similar legal questions or involve the same facts, then the court can set those cases for "joint hearing or trial." This procedure is called "consolidation."

Normally, consolidation happens when several different people file separate lawsuits arising from the same exact factual pattern. For instance, all the people involved in a traffic accident might each file separate law suits for their injuries. Since all these cases would arise from the same traffic accident, the court will "consolidate" them and sort out all the claims in a single proceeding.

To keep using the example of a traffic accident, if all the passengers in the first vehicle file separate law suits in which each claims that the driver of the second vehicle was at fault, then the court will probably lump all those suits together in a way that each "merges" into the others. As a practical and legal matter, this wouldn't deprive these plaintiffs of due process of law, because all are making the same legal claim against the same defendant, and the claims made by each would probably not conflict with the claims of the others.

But what if the driver of the second vehicle sues the people in the first vehicle? In that case, the court could not merge the claim made by the defendant with the claims made by the plaintiffs in the other cases, for the claims would conflict. So, for the claims of the driver of the second vehicle, consolidation must be mean that the cases will remain separate, for the court must make a choice between the conflicting claims.

When the court asked the parties in Adams v. Clinton and in Alexander v. Daley to evaluate whether the cases should be consolidated, the court indicated that it did not intend to merge the two cases into a single case, change the rights of any parties, or make the parties in one suit parties in another. In the long run, however, the court lost sight of Adams v. Clinton.