MR. JUSTICE HOLMES delivered the opinion of the court. The suit in which this writ of prohibition is sought was originally a libel in personam against the petitioner, an Indiana corporation, and others, for causing the death of one Dawson through the capsizing of the steamer Eastland in the Chicago River. The libel was filed on August 21, 1915. A citation was served upon an agent of the petitioner within the district and the petitioner filed exceptions to the libel. On July 24, 1916, leave was granted "to certain parties" to intervene as libellants, and a citation to respondents not served was ordered, returnable the first Monday in September. At this time the petitioner was not subject to service in the district and was not served with process. The "certain parties" mentioned in the order seem to have been 373 other libellants each alleging a distinct cause of action for death due to the same accident. The petitioner excepted that the amended libel was contrary to law because it joined 373 other libellants who had separate causes of action, and also because the petitioner could not in law be called on to answer the amended libel as to 373 additional libellants. The exceptions were overruled and the petitioner directed to answer in twenty days from the date of the order, September 18, 1916. Thereupon the petitioner, not waiving its previous exceptions, on October 7 again excepted that the court had not jurisdiction over it in respect of the additional libellants and that the libel did not state a cause of action against it. On October 25 this petition was filed. The foundation of jurisdiction is physical power. If a defendant's body were in custody by arrest, or a vessel were held by proceedings in rem, it well might be that new claims would be entertained against the person or against the ship, in addition to those upon which the arrest was made. The Oregon, 158 U. S. 186, 210. But appearance in answer to a citation does not bring a defendant under Opinion of the Court. 244 U. S. the general physical power of the court. He is not supposed even by fiction to be in prison. Conventional effect is given to a decree after an appearance because when power once has been manifested it is to the advantage of all not to insist upon its being maintained to the end. Michigan Trust Co. v. Ferry, 228 U. S. 346, 353. That, however, is the limit of the court's authority. Not having any power in fact over the defendant unless it can seize him again, it cannot introduce new claims of new claimants into an existing suit simply because the defendant has appeared in that suit. The new claimants are strangers and must begin their action by service just as if no one had sued the defendant before. The Oregon, 158 U. S. 186, 205, 210. We may repeat with more force concerning defendants what was said alio intuitu in a New Jersey case cited in Reynolds v. Stockton, 140 U. S. 254, 268. "Persons by becoming suitors do not place themselves for all purposes under the control of the court." But it is The only question is whether the petitioner lost its rights by its mode of asserting them; the argument for the respondent being that the exceptions above mentioned amounted to an appearance and plea to the merits, and that thus the absence of service was cured. to be remembered that the motion for leave to intervene was a motion in the cause in which petitioner already had appeared. We should not be astute to treat recognition that it was in court as the case stood before the motion to let in upon it an avalanche of new claims, as waiving what it was the prime and only purpose of the exceptions to prevent. The language of the first exceptions was not as explicit as it might have been but the absence of service seems to us sufficiently covered by the words, "Because the above-named respondent cannot in law, in this case, be called upon to answer the said amended libel as to 373 additional libellants." . The second exception, still insisting on the petitioner's denial that the court had jurisdiction of it in respect of the new claims set up, pleaded further, upon the rule to answer, that the amended libel did not state a cause of action. But if the principles of waiver and appearance by pleading to the merits are not modified in a case where the defendant already is in court, it is true at least that when objections to the jurisdiction have been overruled the defendant does not lose its rights by pleading to the merits. Harkness v. Hyde, 98 U. S. 476. The District Court attempted to exceed its jurisdiction and the writ of prohibition should be granted. Rule absolute. PAINE LUMBER COMPANY, LIMITED, ET AL. v. NEAL, INDIVIDUALLY AND AS SECRETARY AND TREASURER OF THE JOINT. DISTRICT COUNCIL OF NEW YORK AND VICINITY OF THE UNITED BROTHERHOOD OF CARPENTERS AND JOINERS OF AMERICA AND AMALGAMATED SOCIETY OF CARPENTERS AND JOINERS OF AMERICA, ET AL. APPEAL FROM THE CIRCUIT COURT OF APPEALS FOR THE SECOND CIRCUIT. No. 24. Argued May 3, 4, 1915; restored to docket for reargument June 12, 1916; reargued October 24, 25, 1916.-Decided June 11, 1917. A private party cannot maintain a suit for an injunction under § 4 of the Sherman Anti-Trust Law. Such action upon the part of a labor union as is involved in this case is not subject to be enjoined under the laws of New York in a private suit. 214 Fed. Rep. 82, affirmed. THE case is stated in the opinion. Argument for Appellants. 244 U. S. Mr. Walter Gordon Merritt and Mr. Daniel Davenport for appellants: The combination falls within that class of restraints of trade intended to coerce third parties and strangers from engaging in interstate trade except on conditions that the combination imposes, and therefore violates the Federal Anti-Trust Law. The object is to control conditions of manufacture by preventing the sale and use of manufactured articles unless they come from mills operated and exclusively manned by members of the combination. It is a combination between the sources of production and those who control distribution and consumption, to limit the market to producers joining such combination. According to the defendants' contention, they must protect the union mills from the competition of non-union mills because, under the natural law of trade and competition, the union mills cannot survive with their increased cost of production. The rule against using or working on open shop "trim" was therefore adopted to destroy open shop competition. The Master Carpenters' Association also take active steps to enforce this régime in order to protect themselves from the competition of independent contractors using such material. The conceded purpose is to increase profits and wages in the union mill and to do this by the only possible method by which men working on buildings could accomplish such a purpose, viz: restraining trade or commerce by making open shop products unsalable. There is no relation between the buildings and the factories except commerce, so that the only way in which the conditions in the mills can be affected by the conduct of the men at the buildings is by controlling commerce. The union manufacturers and their employees have an undoubted interest in extending the sale and use of any merchandise which is produced by their joint efforts, 244 U. S. Argument for Appellants. and may, therefore, justify and excuse any injury which they inflict upon their competitors by the ordinary methods of legitimate competition. They cannot, however, by association or combination with journeymen who have no such interest, but exercise a despotic control over the use and installation of such products, destroy the competition of business rivals and monopolize the market. This is no ordinary labor case, but an instance where the defendants are seeking to project their influence into trade and commerce for the purpose of preventing the sale and distribution of completed articles of common use produced by their competitors. It is an attempt to drive open shop products out of commerce. The distinction between a combination where parties subject themselves to a self-imposed restraint, and a combination which has also the objective purpose of interfering with outsiders, has been recognized by this court, which holds that the latter combination implies a wrongful purpose. United States v. Patten, 226 U. S. 525; Loewe v. Lawlor, 208 U. S. 274; Northern Securities Co. v. United States, 193 U. S. 197; Standard Oil Co. v. United States, 221 U. S. 1; Thomsen v. Union Castle Mail S. S. Co., 166 Fed. Rep. 251; State v. Duluth Board of Trade (Minn.), 121 N. W. Rep. 395; Brown & Allen v. Jacobs Pharmacy (Ga.), 41 S. E. Rep. 553. If the object of the combination be the illegal one described, it is immaterial that the means are otherwise innocent and lawful. There is nothing talismanic about the right to strike which excepts it from this universal and wholesome rule of law. Aikens v. Wisconsin, 195 U. S. 204; Gompers v. Bucks Stove & Range Co., 221 U. S. 418; Swift & Co. v. United States, 196 U. S. 375; United States v. Reading Co., 226 U. S. 324; Loewe v. Lawlor, supra. This doctrine that an act otherwise legal may become illegal when exercised in furtherance of an illegal con |