John A. Thornton appeals his conviction for unlawful possession of a controlled substance (cocaine) with intent to distribute, a violation of 21 U.S.C. Sec. 841(a). Thornton challenges his conviction on two grounds. First, he contends that the district court's acceptance of a blanket fifth amendment privilege, asserted by an important defense witness, violated his sixth amendment right to compulsory process. Second, Thornton claims that the district court improperly denied his motion to suppress evidence taken from his person because, according to Thornton, the search that produced the evidence was unconstitutional. For the reasons set forth below, we find that both of Thornton's challenges lack merit.I. BACKGROUND

In the early evening on March 16, 1983, Detective Leon Owens of the Metropolitan Police Department (MPD) and several other police officers entered an apartment building in Southeast Washington, D.C. in order to execute a search warrant for a particular apartment in the building. While the other officers positioned themselves to enter the apartment, Detective Owens stood in the hallway just inside the front door of the building. From this vantage point, Owens saw two men, later identified as Thornton and Charlie Cowser, walking up the stairway from the basement. When the two men reached the top of the stairs, both looked startled, and Cowser yelled, "Police!"1 At this time, according to Owens' testimony, Owens saw Thornton place a small plastic package that resembled "the way narcotics are packaged on the street" into the right rear pocket of his pants. Tr. 18.

Owens stopped Thornton, advised him of his rights, and explained that he was not yet under arrest. Owens then began to "pat down" the appellant's coat, and removed a camera from his coat pocket. After ordering Thornton to turn around, Owens next lifted the back of Thornton's coat and removed the plastic package from his right rear pants pocket. Owens noticed that the package contained several rolled-up plastic bags of white powder. Suspecting that the package contained narcotics, Owens arrested Thornton. Owens then conducted a more thorough search of Thornton incident to the arrest, and found another similar package in his right coat pocket.

At a pretrial suppression hearing, Thornton testified that prior to his arrest he and Cowser had been in Cowser's basement apartment, where he had injected heroin and cocaine. While Thornton admitted that he was carrying narcotics when he was arrested, he testified that he had placed the packages containing the narcotics in his pockets and had securely fastened his jacket before he began to walk up the stairs. Thornton therefore asserted that Owens could not have seen him place a package in his back pocket, and argued that Owens had lacked probable cause to conduct the initial search that resulted in the arrest.

Alvonia M. Branch, who lived in Cowser's basement apartment, testified on behalf of the defense. She said that Cowser had left the apartment alone to play the lottery, and that just after he left, she came out of the apartment to give him another lottery number. According to Branch, she then saw both Cowser and Thornton at the top of the stairs. While acknowledging that she did not pay attention to what Thornton did with his hands, Branch testified that she did not see him reach into his pocket.

In an attempt to corroborate further his account of the facts, Thornton called Cowser as a witness. After preliminary questioning, however, Cowser, who had been arrested at the same time as Thornton for possession of cocaine and drug paraphernalia, invoked the fifth amendment privilege against self-incrimination, and refused to answer the question posed by the defense attorney, "Would you, at this point, tell His Honor what happened at that time [i.e., the time of Thornton's arrest]?"2 The district judge, recognizing that Cowser was at that time facing charges in the Superior Court for the District of Columbia arising out of the same events, sustained Cowser's refusal "to testify any further about any involvement or your activities on the evening in question," Tr. 51, despite the likelihood that Cowser could be a "vital witness" for the defense in the suppression hearing, Tr. 54.

After the pretrial hearing, the district court denied Thornton's motion to suppress evidence. Finding that Detective Owens' testimony represented "the credible version of what happened that evening,"3 the district court held that the search of Thornton and the seizure of evidence had been based on a reasonable suspicion, supported by objective and identified circumstances, that Thornton was engaged in criminal activities. See United States v. Thornton, Crim. No. 83-00053 (June 20, 1983). After this ruling, Thornton agreed to a stipulated trial. See United States v. Thornton, Crim. No. 83-00053 (July 15, 1983) (Stipulation of Evidence). The district court found Thornton guilty, and sentenced him to a three-year prison term, with an additional three-year term of special parole. This appeal followed.

II. COWSER'S FIFTH AMENDMENT PRIVILEGE AND THORNTON'S SIXTH

The Constitution establishes the right of a criminal defendant "to have compulsory process for obtaining witnesses in his favor." U.S. Const. amend. VI. As the Supreme Court has elaborated, "[t]he right to offer the testimony of witnesses, and to compel their attendance, if necessary, is in plain terms the right to present a defense." Washington v. Texas, 388 U.S. 14, 19, 87 S. Ct. 1920, 1923, 18 L. Ed. 2d 1019 (1967); see Chambers v. Mississippi, 410 U.S. 284, 302, 93 S. Ct. 1038, 1049, 35 L. Ed. 2d 297 (1973).

The accused's right to compulsory process, however, does not include the right to compel a witness to waive his fifth amendment privilege. See, e.g., United States v. Reese, 561 F.2d 894, 899-900 (D.C.Cir.1977); Bowles v. United States, 439 F.2d 536, 541-42 (D.C.Cir.1970) (en banc) (right to compulsory process does not include right to have the witness assert fifth amendment privilege before the jury, let alone to have the witness testify), cert. denied, 401 U.S. 995, 91 S. Ct. 1240, 28 L. Ed. 2d 533 (1971). The issue in this case, however, is not whether Cowser retained his fifth amendment privilege; rather, it is whether the district court acted properly in sustaining Cowser's claim of privilege as to his entire testimony regarding the circumstances of Thornton's arrest. For the reasons explained below, we find that the district court acted well within its discretion in determining the proper scope of Cowser's fifth amendment privilege.

As this court has observed, when balancing the sixth amendment right of the accused and the fifth amendment right of the witness, "the trial judge must make an appropriate inquiry into the basis of the privilege claimed by the witness, and may not permit the witness to refuse to testify where a narrower privilege will adequately protect him." United States v. Reese, 561 F.2d at 900; see also United States v. Moore, 682 F.2d 853, 856 (9th Cir.1982); United States v. Melchor Moreno, 536 F.2d 1042, 1046-47 (5th Cir.1976). We believe that the district court satisfied this standard under the circumstances of this case. At the time of the hearing, Cowser was facing charges pending against him for possession of cocaine and paraphernalia found on his person at the same time as Thornton's arrest. Accordingly, if Cowser had testified about the circumstances of Thornton's arrest, it is difficult to see how he could have avoided testifying about the circumstances of his own arrest, a topic obviously within the scope of his fifth amendment privilege.4

Thornton nevertheless contends that "because the trial court in this case made no effort to determine if there were limited areas about which Cowser could safely testify, and because it is apparent from the record that such areas exist," the case should be remanded to give the defense an opportunity to pursue a narrower line of inquiry that might be outside the scope of Cowser's fifth amendment privilege. Appellant's Brief at 11. Specifically, appellant suggests that Cowser might testify narrowly as to "whether Thornton put an object in his pocket immediately before his arrest, as Owens had testified." Id. at 16.

To sustain the invocation of the fifth amendment privilege, the district judge must determine only whether there is a reasonable basis for believing a danger to the witness might exist in answering a particular question, for "if the witness, upon interposing his claim, were required to prove the hazard ... he would be compelled to surrender the very protection which the privilege is designed to guarantee." Hoffman v. United States, 341 U.S. 479, 486, 71 S. Ct. 814, 818, 95 L. Ed. 1118 (1951); see Reese, 561 F.2d at 900. When the witness refuses to answer a particular question, the trial judge has a duty to determine whether a narrower privilege would suffice to protect the witness from danger while permitting the defendant to elicit desired testimony. See Reese, 561 F.2d at 900; see also Moore, 682 F.2d at 856; Melchor Moreno, 536 F.2d at 1049. Usually, a trial court cannot speculate whether all relevant questions would or would not tend to incriminate the witness; accordingly, the court normally requires the privilege to be asserted in response to specific questions. In unusual cases, however, a district judge may sustain a blanket assertion of privilege after determining that there is a reasonable basis for believing a danger to the witness might exist in answeringany relevant question. See, e.g., Reese, 561 F.2d at 899-900 (blanket privilege sustained because "the only relevant matters" that the witness might have testified about were all privileged); United States v. Tsui, 646 F.2d 365, 367-68 (9th Cir.1981) (trial court may accept blanket privilege where, "based on its knowledge of the case and of the testimony expected from the witnesses, [it] can conclude that the witness could 'legitimately refuse to answer all relevant questions' ") (quoting United States v. Goodwin, 625 F.2d 693, 701 (5th Cir.1980)), cert. denied, 455 U.S. 991, 102 S. Ct. 1617, 71 L. Ed. 2d 852 (1982).

We believe that the district court properly concluded that any testimony relevant to the circumstances surrounding Thornton's arrest could tend to compromise Cowser's ability to defend himself against pending criminal charges. It is the trial judge's role and responsibility to assess the plausibility of the claim of fifth amendment privilege:

We find no merit in [the appellant's] assertion that the court erred in supposing that [the witness'] testimony might actually tend to incriminate him. A trial judge may appraise a claim of privilege in light of his "personal perception of the peculiarities of the case" and should not be overruled unless it is "perfectly clear" that the witness is mistaken and that the answer "cannot possibly" incriminate.

Reese, 561 F.2d at 900 (quoting United States v. Johnson, 488 F.2d 1206, 1209 (1st Cir.1973)); Bowles v. United States, 439 F.2d at 541-42. Given the "peculiarities of th[is] case"--that the defendant and the witness were arrested at the same time on similar charges, arising out of activities in which they very well might have been jointly involved5--we do not think it "perfectly clear" that Cowser would not have incriminated himself had he testified as to any relevant events.

Thus, we do not think the district judge erred in sustaining Cowser's blanket assertion of privilege. Given the determination that Cowser could legitimately assert the privilege as to any relevant question, and given that Cowser did assert such a privilege, we do not think the district judge was under an obligation to subject Cowser to a searching inquiry for the purpose of determining whether he would choose not to assert the privilege to which he was entitled. Indeed, such a procedure could be seen as an attempt to intimidate or harass the witness into waiving his constitutional rights. Perhaps if the defense counsel had proffered a particular line of questioning, supported by reasons to believe that the witness would not invoke his fifth amendment privilege as to those questions, the district judge might have permitted such questioning. In this case, however, the defense counsel made no such proffer; instead, the defense counsel asked broadly, "Would you, at this point, tell His Honor what happened at that time?"6 Tr. 18.

Accordingly, we uphold the district court's ruling on the scope of Cowser's fifth amendment privilege.

III. THE DISTRICT COURT PROPERLY DENIED THORNTON'S MOTION TO

Thornton also contends that the searches of his person conducted by Owens were unconstitutional. He claims that Owens' initial search was an unconstitutional warrantless search, (1) not supported by probable cause and (2) not qualified as a "stop and frisk" search under Terry v. Ohio, 392 U.S. 1, 88 S. Ct. 1868, 20 L. Ed. 2d 889 (1968). Thornton further argues that the subsequent search incident to arrest was likewise unconstitutional, since the arrest was tainted by the initial search. See Wong Sun v. United States, 371 U.S. 471, 83 S. Ct. 407, 9 L. Ed. 2d 441 (1963).

Thornton's argument thus relies on his claim that the initial search was unconstitutional. Because we find that the initial search was supported by probable cause, we affirm the district court's ruling.7

As a general rule, probable cause to search "exists when circumstances known to a police officer are such as to warrant a person of reasonable caution in the belief that a search would reveal incriminating evidence."8 United States v. McEachin, 670 F.2d 1139, 1142 (D.C.Cir.1981) (quoting United States v. Hawkins, 595 F.2d 751, 752 n. 2 (D.C.Cir.1978) (per curiam)). Under this test, we think that Owens had probable cause to conduct the initial search of Thornton. Owens saw Thornton put a package resembling narcotics in his back pocket. Cf. Texas v. Brown, --- U.S. ----, 103 S. Ct. 1535, 1538, 75 L. Ed. 2d 502 (1983) (probable cause when officer noticed "green party balloon knotted about one half inch from tip" and was "aware that narcotics frequently were packed in [such] balloons"). Owens, a fourteen-year veteran of MPD who had participated in narcotics work for eight years, was quite familiar with common methods of packaging and storing narcotics. Thornton looked startled and placed the package in his back pocket after someone yelled, "Police!" Probable cause is a "flexible common sense standard," Texas v. Brown, 103 S. Ct. at 1543, which we believe was clearly satisfied by the circumstances of this case, especially considering that Owens entered the apartment building to execute a search warrant for narcotics, and therefore had further cause to be suspicious of Thornton's behavior.9 See United States v. Juarez, 573 F.2d 267, 274-75 (5th Cir.), cert. denied, 439 U.S. 915, 99 S. Ct. 289, 58 L. Ed. 2d 262 (1978). Accordingly, we find that the initial search of Thornton was constitutional, and, because the initial search resulted in the discovery of contraband, the subsequent arrest and search were also permissible.

For the reasons set forth above, we find the district court properly sustained Cowser's claim of privilege and denied Thornton's motion to suppress.

So ordered.