delivered the opinion of the Court.

This is an action of trespass for assault and false imprisonment. There are five bills of exception in the record. Two relate to rulings of the Superior Court on prayers for instructions to the jury and three to the admissibility of proffered, but rejected evidence. About some of the facts there is dispute and conflict. To these facts reference will be made as we proceed. They have relation to the ruling in the' first, and to some of the rulings in the fifth bill of exceptions. The uncontroverted facts, that are material to an intelligent presentation of the questions involved in all the rulings complained of, may be concisely summarized from the record without quoting extensively or literally from its pages.

Two of the defendants, Henry C. Kirk and Henry C. Kirk, Jr., constitute the firm of Samuel Kirk & Son, manufacturers and dealers in silverware. The equitable plaintiff, a youth of some seventeen or eighteen years of age, was one of their employees, and his duty was to polish the finished work. The other two defendants, Miller and Hardesty, were members of a detective agency; one of them, Hardesty, being a constable. The Messrs. Kirk discovering that they were being subjected to repeated losses by larcenies believed to have been committed by persons in their service, the junior member of the firm engaged Miller and Hardesty to investigate and to ascertain, if possible, the culprits. On the last day of July, 1894, the equitable plaintiff took from the shop of Kirk & Son a half dozen silver tablespoons concealed in his pocket, and on the corner of *403Saint Paul and Fayette streets handed them to a co-employee to be engraved, the engraver having previously refused to take them from the plaintiff whilst in the defendants’ shop. The detectives saw the plaintiff leave the shop with something hidden in the inside pocket of his coat, and they also saw him give the package to the engraver on the street corner. The next day the plaintiff on leaving the shop again took with him six tablespoons, which he carried, as before, in the inside pocket of his coat. As he proceeded up the street on his bicycle he heard a whistle, and on looking around saw Hardesty, who motioned to him to stop. He did stop and Hardesty went up to him, showed his badge as a constable and requested the equitable plaintiff to accompany him to his, Hardesty’s office. Thereupon Miller joined them and the three walked to the office of Miller and Hardesty, not far distant. When they reached there and entered with the plaintiff, they locked the door and then asked him whether he had any spoons in his possession. He replied that he had and produced a half dozen tablespoons from his inside pocket; whereupon the detectives charged him with having stolen them, which charge he denied and claimed that, though the spoons were stamped with the name of Samuel Kirk & Son, and were Kirk’s silver, he had exchanged for them, without the knowledge of his employers, an equal amount in weight of old silver. Mr. Kirk, Junior, was then sent for, and upon his arrival made inquiries as to whether other employees had been guilty of stealing, and the plaintiff, according to one of his versions of the interview, informed Mr. Kirk that five others had exchanged old silver for manufactured silver, just as the plaintiff said he had done; but according to the version of the interview given by Mr. Kirk and by Mr. Miller and Mr. Hardesty, the plaintiff admitted that five other employees were guilty'of stealing articles from Kirk & Son’s shop, and he gave the names of the parties and described the articles, and signed a paper setting forth this information. He was then taken to Brawner’s Hotel, as he says, without his con*404sent and against his will; but as the other three declare, at his own instancetand request. He was told by the detectives immediately after his arrest, so they and Mr. Kirk assert, that they would be obliged to take him to the station-house to be dealt with by the Police Department; but he appealed to Mr. Kirk to prevent this being done, as his arrest, if thus given publicity, would become known to his invalid mother and the shock would probably cause her death. In consequence of this appeal, in view of his youth and upon his promise to appear before the grand jury and there testify against his co-employees, Mr. Kirk, Junior, consented that he should not be taken to the station-house ; and the plaintiff himself suggested that he should be allowed to go with the detectives to a hotel and be there kept until he could give his testimony before the grand jury. He was taken to Brawner’s Hotel and remained there all night. The next day he went back to Miller and Hardesty’s office with them and staid there the entire day, and the night of that day he spent, still in the company of the detectives, at the Imperial Hotel. The next day he went before the grand jury and testified, though, as he now says, he did not then inform the grand jury that the other men, named by him to Mr. Kirk, had been stealing from the firm. After appearing as a witness before the grand jury he was permitted to return to his home, no accusation was lodged against him and he was reinstated by the firm, in his position as an employee, where he remained until' within a day or two before this suit was instituted, on the following twenty-first day of September. Henry C. Kirk, Senior, had no knowledge of the arrest of the equitable plaintiff when it was made, and according to the undisputed evidence had nothing to do with it; nor does he appear to have known'what was done with the plaintiff when he was taken into custody.

The spoons found in the possession of the equitable plaintiff when he was arrested were beyond doubt the property of Samuel Kirk & Son. They had been made for them out of their own silver, by their own workmen ; bore their *405trade mark, and the cost of their manufacture had been paid by the firm. That an employee, without their knowledge or consent could surreptitiously take and carry away this property upon leaving with a fellow workman in its place and stead raw material equal in weight but not the equivalent in value of the manufactured article, and yet be innocent of the crime of larceny is a doctrine which finds no countenance or sanction in the law. When, therefore, the equitable plaintiff took and carried away from the shop of Kirk 8c Son on the thirty-first of July one-half dozen tablespoons and again on the day following an additional half dozen, he was incontestibly guilty of larceny. If so guilty was his arrest or detention lawful or illegal ?

The illegality of the arrest and the unlawfulness of the detention are indispensible elements in this form of action; and if, therefore, the arrest were lawful and the detention were reasonable there was, and could be in the very nature of the case, no false arrest or false imprisonment. From the earliest dawn of the common law a constable could arrest without warrant when he had reasonable grounds to suspect that a felony had been committed ; and he was authorized to detain the suspected party such a reasonable length of time as would enable him to carry the accused before a magistrate. And this is still the law of the land. It is wholly immaterial whether the suspicion arises out of information imparted to the constable by some one else, or whether it is founded on the officer’s own knowledge. In either event what amounts to a sufficient ground of suspicion to justify an arrest, by a constable, without a warrant, is for the Court and not for the jury to determine. In Pollock on Torts this doctrine is thus stated: “ What is reasonable cause of suspicion to justify arrest is—paradoxical as the statement may look—neither a question of law nor of fact. Not of fact, because it is for the Judge and not for the jury (citing Hailes v. Marks, 7 H. & N. 56); not of law, because no definite rule can be laid down for the exercise of the Judge’s judgment (citing Lister v. Perryman, L. R. 4 H. L. *406521, per Lord Chelmsford and Lord Colonsay). It is a matter of judicial discretion such as is familiar enough in the classes of cases which are disposed of by a Judge sitting alone; but this sort of discretion does not find a natural place in a system which assigns the decision of facts to the jury and the determination of the law to the Judge. The anomalous character of the rule has been more than once pointed out and regretted by the highest judicial authority.” Lord Campbell in Broughton v. Jackson, 18 Q. B. 378; Lord Hatherly, Lord Westbury and Lord Colonsay in Lister v. Perryman, supra. “ But,” continues the author, “ it is too well settled to be disturbed unless by legislation.” Pollock on Torts, 192 (edition of 1887); Cohen v. Huskisson, 2 M. & W. 477; Warner v. Reddiford, 4 C. B. n. s. 180; Mure v. Kaye, 4 Taunt. 34; 2 Addison on Torts, sec. 841. It may be broadly stated that what amounts to probable cause in cases of malicious prosecutions will amount to such reasonable grounds for suspicion of felony as will justify and require an officer to make an arrest. Reg. v. Dadson, T. & M. 385; 2 Am. & Eng. Ency. Law, 871 (second edition).

Now, do the facts show that Hardesty, the constable, had reasonable grounds to suspect that a felony had been committed and that the equitable plaintiff was the guilty party ? If they do, the arrest, though made without a warrant, was lawful. The constable had been informed by the younger Mr. Kirk that larcenies were being committed, and he saw, the day preceding the arrest, the plaintiff come from the shop with something concealed in the inner pocket of his coat, and he further saw this package delivered on the street corner to another employee whom Miller followed and found to be Kirk’s engraver. And then on the day of the arrest he saw the plaintiff with something again concealed in his pocket and upon arresting him found in his possession the spoons that belonged to Samuel Kirk & Son. Here then was a case where the plaintiff had actually stolen his employer’s property—for as we have already said his taking of *407the spoons even under the conditions testified to by himself was indisputably a larceny—and he was found with the stolen property in his possession. There was, therefore, not only reasonable ground to suspect that a felony had been committed, but there was clear and conclusive evidence of the fact that the equitable plaintiff was guilty; and had the officer taken the accused in a reasonable time before a magistrate to be committed or bailed for his appearance to answer the charge, the case would, on the plaintiff’s own showing, have been at an end.

It cannot be questioned that when a person is arrested either with or without a warrant, it becomes the duty of the officer or the individual making the arrest to convey the prisoner in a reasonable time and without unnecessary delay, before a magistrate to be dealt with as the exigency of the case may require. The power to make the arrest does not include the power to unduly detain in custody; but on the contrary is coupled with a correlative duty, incumbent on the officer, to take the accused before a magistrate “ as soon as he reasonably can.” 1 Hilliard on Torts, 223, sec. 19; Wright v. Court, 4 B. & C. 596; Firestone v. Rice, 71 Mich. 377; B. & O. R. R. Co. v. Cain, 81 Md. 87; Twilley v. Perkins et al., 77 Md. 252; Rohan v. Sawin, 5 Cush. 281; Com. Dig. Imprisonment, H. 4. If the officer fails to do this and unreasonably detains the accused in custody he will be guilty of a false imprisonment no matter how lawful the original arrest may have been. 1 Hil. Torts, 213—214, sec. 9.

We are brought, then, to the prayer presented by the defendant at the close of the plaintiff’s evidence. It asked an instruction that the plaintiff was not entitled to recover, but was rejected by the Trial Court; and this is the ruling brought up for review by the first bill of exceptions. At the close of the evidence on both sides the defendants again offered the same prayer and it was again rejected, and this is one of the imputed errors complained of in the fifth bill of exceptions. Before such a prayer can be granted in any *408case all the plaintiff’s evidence must be assumed to be true; and if, when conceded to be true, it fails to show a right on his part to recover, it then becomes the duty of the Court to withdraw the case from the consideration of the jury. But here, according to the plaintiff’s own testimony, though he himself showed that he had been rightly arrested, he protested against being detained in the custody of the detectives ; and if his statement in this particular be accepted as true, and this must be done for the purpose of determining whether such a prayer as we are now considering ought to be granted, then he was detained for an unreasonable length of time even though the detention was designed merely to secure his appearance before the grand jury. If, upon condition of his furnishing evidence that would lead to the arrest and conviction of other guilty parties it was, with the sanction of the State’s Attorney, determined not to prosecute him, then he should have been taken before a magistrate to make formal complaint against the others, and he should not have been held in custody against his will for his appearance before the grand jury, unless upon his failure to give a recognizance when lawfully required by a justice of the peace, for his appearance as a witness. In the face of his testimony, the credibility of which was for the jury alone to pass on, it would have been erroneous to grant the prayer set forth in the first exception. The defendants proved by three witnesses in the most conclusive and satisfactory manner that the plaintiff was not taken before a magistrate only because he besought Mr. Kirk not to so deal with him, and that he himself suggested his willingness to go to a hotel and to remain there and with the detectives until he could appear before the grand jury. Here, then, was a direct conflict of testimony. It was for the jury to say whether they would believe the plaintiff, on the one hand, or the three witnesses who flatly contradicted him, on the other. The Court could not, under these conditions,. withdraw the consideration of that question from, the jury; and, therefore, could not grant the defendant’s *409first prayer in the fifth bill of exceptions—that prayer being the same one presented at an earlier stage of the case and set forth in the first exception.

Had, however, the jury found as a matter of fact, as they were clearly at liberty to do from the evidence before them, that the equitable plaintiff voluntarily remained in custody in order to appear before the grand jury as a witness, just as Mr. Kirk, Mr. Miller and Mr. Hardesty unequivocally testified was the case, then he was not unlawfully restrained of his liberty. False imprisonment consists in the unlawful detention of one against his will. Where there is no restraint and where the individual of his own free choice and volition remains where he is, though at liberty to depart if he pleases, he is not imprisoned at all. The defendants, therefore, had the undoubted right to have that view of the law submitted to the jury and the refusal of the Court to grant their third, fourth and fifth prayers embodying that principle, deprived them of a substantial defence and was clearly erroneous.

The second prayer of the defendants ought also to have been granted. It sought an instruction to the effect that there was no legally sufficient evidence in the case to maintain the action against the firm of Samuel Kirk & Son or Henry C. Kirk, Senior, one of the members thereof. The evidence, as we have stated, failed to show that the senior Mr. Kirk knew anything about the arrest or detention of the plaintiff, or that he ratified it afterwards. There is literally nothing in the whole record connecting him in any way with the transaction from Its beginning to its end. One of several partners cannot drag the firm or his co-partners into a trespass by giving authority for the doing of an unlawful act in the name of the firm of which he is a member; for one partner has no power to bind the partnership to the commission of a wrongful act without the previous consent or subsequent concurrence of all the partners. Petrie v. Lamont, Car. & Marsh, 96. If the act complained of is done by one partner for the benefit of the *410firm, and the firm afterwards takes advantage of it and adopts the transaction, all the members of the firm may-then become responsible for the act and its consequences. 2 Addison on Torts, sec. 1321. If all the partners join in one trespass or tort they may all be sued for the injury, not because they are partners, but because the right of action arises from their personal misconduct. " In general,” says Collyer on Part., sec. 457, “ acts or omissions in the course of the partnership, trade or business, in violation of law, will only implicate those who are guilty of them.” And in Parsons' Principles of Partnership, sec. 140, the rule is succintly stated in this way: “ If the firm is merely the occasion for a partner’s tort, but not the agency in its commission, the copartners are not liable.” Obviously under the proof in the record the firm of Samuel Kirk & Son was not the agency in the alleged unlawful arrest and imprisonment, nor was Henry C. Kirk, Senior. The thefts from the firm were the occasion for the arrest, and unless you identify that occasion with the agency that actually caused the arrest there is nothing to connect the firm or the senior partner with the transaction.

The plaintiff’s second prayer ought to have been rejected because it not only disregards the principle just stated, but in spite of that principle, holds the firm, and each of the members thereof, liable if one partner aided, participated in and approved of the detention of the equitable plaintiff. The third prayer of the plaintiff relates to the measure of damages and is, in so far as it would not embrace the firm and the senior Mr. Kirk, free from objection.; but inasmuch as its terms are broad enough to include both the firm and Mr. Kirk, Senior, it ought to have been modified, so as to exclude them; or, not being qualified in that way, should have been rejected altogether. The plaintiff’s first prayer is also erroneous. In effect it leaves to the jury the determination of the question as to whether the arrest and detention were lawful. It permits them to take the facts and circumstances of the case and from a consideration of them *411to say whether these were such facts and circumstances as in their opinion would have induced “ a reasonable and dispassionate man to have made such arrest and to have so detained the said Garrett;” whereas, in cases of this character, it is for the Court to say whether a given state of facts, if found by the jury, is in law sufficient to create a reasonable ground of suspicion that will justify a constable in making an arrest without a warrant, and whether a detention is or is not unreasonable.

This disposes of all the prayers and we turn now to the three remaining exceptions which relate to the admissibility of the rejected evidence offered by the defendants. The second exception was taken to the refusal of the Court to allow a question to be asked the witness, Miller, relative to six silver teaspoons alleged to have been stolen by one of the other employees of Samuel Kirk & Son. The ground upon which it was claimed the question was admissible was that the spoons were discovered through the equitable plaintiff’s instrumentality. This we think was irrelevant. It tended to prove ho issue in the case and was wholly collateral thereto.

The fourth exception brings up the ruling of the Court, refusing to admit in evidence the indictments found by the grand jury against other employees of Kirk & Son. These indictments charged the accused with larceny, and amongst the names of the witnesses endorsed thereon was that of the equitable plaintiff. The proof of this fact would have reflected no light on the issues joined in this case. The accusations against these other men, as contained in formal indictments, could not tend to show the guilt of the equitable plaintiff, or that he was lawfully arrested or detained only for a reasonable time. Because of the irrelevancy of the proffered evidence the Superior Court rightly refused to admit it.

The third exception presents, however, a different question. The plaintiff had testified that whilst in custody, and shortly after his arrest, he had informed Mr. Kirk, in the *412presence of the detectives, that he knew of other employees stealing silver, but that he was so intimidated by the threats they made to send him to the penitentiary, he scarcely knew what he said. He further testified that when he went before the grand jury he told them he could not say positively that any of the workmen had been stealing; but that he knew they had had things made there the same as he had.- Now, the contention of the defendants was that the' plaintiff was not prosecuted for the larceny he had committed because he agreed to give information which would lead to the conviction of others ; and that he voluntarily remained with Miller and Hardesty until he could go before the grand juiy. When he took the witness-stand in his own case, he in effect, denied that he had given any evidence before the grand jury implicating others, and he emphatically denied that he voluntarily remained in custody. One of the grand jurors was thereupon called by the defendants, and was asked what the plaintiff had testified to before the grand jury, as to the charges against these men ? To the admissibility of this question an objection was interposed, and upon the counsel for the defendants stating, in reply to an inquiry by the Judge, that he did not know what the juror would say, the objection was sustained. We think there was error in this ruling. The plaintiff, as we have seen, admitted that he had given information against his ■ co-employees, and that he had given it as a condition of his not being prosecuted, and three of the defendants had unequivocally sworn that the plaintiff voluntarily remained with the detectives until he could go before the grand jury to testify. Subsequently, in his testimony in this case, he denied that he had told the grand jury what Mr. Kirk and the detectives said he had revealed to them ; and thus it became' important to know what he did say before the grand jury; both for the purpose of contradicting him on a material matter of fact, and also for the purpose of showing that he had in reality voluntarily remained in custody precisely as it was alleged by the defendants, that he agreed to *413do. If he made admissions before the grand jury that showed he voluntarily remained in custody, it was clearly competent to offer those admissions in evidence as independent facts, defeating his right to recover, even though he had not been first interrogated with respect to them when giving his testimony in this trial. The admissions of a party to the record made against his own interest stand on a different footing from the statements of a mere witness. A witness cannot be impeached by the proof of contradictory statements previously made by him, unless he is first asked with regard to them, and has his attention called to the time and place when and where, and the person to whom or in whose presence the statements were made. But the admissions of a party to the cause, adverse to his right to recover, may always be shown without first questioning him concerning them. Bartlett & Robbins v. Wilbur, 53 Md. 497. The two classes of admissions are wholly dissimilar. In the case of a witness, his contradictory statements are admissible not to prove a specific fact, but solely for the purpose of impeaching him. In the case of a party they are admissible to prove a fact adverse to his right to maintain the suit. Under the circumstances already alluded to, the calling of a grand juror to testify as to what the plaintiff had deposed to before the grand jury, was not in contravention of any rule of law, and not repugnant to public policy. A grand juror may be called to prove that a witness swore in the grand jury room differently from the way he has sworn before the petit jury, and this is no violation of the grand juror’s oath of secrecy. As we said in Izer’s case, 77 Md. 110, the grand juror’s oath of secrecy is intended to further and not to frustrate the due administration of justice; and whilst its observance is obligatory on him and binds him for all time not to voluntarily disclose what has transpired in the jury room, it cannot be invoked to thwart the truth or to mask and cover up falsehood, when the juror is called upon in a Court of justice to divulge what he would otherwise, but for the mandate of the law com*414pelling him to speak, be bound to keep secret. The inability of the defendants’ counsel to state to the Court what the grand juror would prove, furnished no reason for the exclusion of the evidence. The counsel could not have known what the grand juror would testify to, unless the latter had, in violation of his oath, previously revealed it.

For the errors indicated in rejecting the defendant’s second, third, fourth and fifth prayers, and in granting the plaintiff’s first and second and in not restricting and qualifying the third, as also for the error in excluding the evidence proposed to be given as noted in the third bill of exceptions, the judgment in favor of the plaintiff must be reversed and a new trial must be had.

Judgment reversed with costs above and below and new trial awarded.