delivered the opinion of the Court:

The question for determination is whether the second interference related to substantially the same cause of action as the prior interference. If it did, the decision in the first is *344conclusive in the second as to every question which was or might have been presented or determined in the first. Blackford v. Wilder, 28 App. D. C. 535; Horine v. Wende, 29 App. D. C. 415. In Blackford v. Wilder the unsuccessful party in a former interference, upon the cause going back to the Patent Office, amended and broadened his claims, but it was held that the decision in the prior interference was conclusive of his rights, because he might have made the broader claims in that interference. In that case the amendment was to the same application involved in the first interference, but that is of no importance if, in fact, the subject-matter disclosed in the two applications is substantially the same. New Departure Mfg. Co. v. Robinson, 39 App. D. C. 504. The Patent Office tribunals have successively ruled that the second interference relates to substantially the same cause of action as the first. In his decision the Commissioner said: “He (Cross) contested the earlier interference, knowing that under the practice of the Office the winning party would be entitled to present broader claims, and it is not seen how Rusby can be deprived of that right by the fact that a patent was granted on the earlier Cross application. Had Cross presented the claims here in issue in his later application after the termination of the first interference, they would have been at once rejected on the ground that the question of priority as to these claims was res judicata between himself and Rusby. The fact that these claims were [presented in another application puts him in no better position.” Assuming, for the purposes of this decision, that the claims of the second interference are slightly broader than those of the former, although there is much force'in the contention of counsel for Rusby thatthe difference is one of expression rather than of fact, we concur in the Commissioner’s conclusions.

Decision affirmed. Affirmed.