When will a court compel disclosure of the identity of an informant at trial?

The requirement of pretrial disclosure of an informant's identity is set forth in Roviaro v. United States, 353 U.S. 53, 77 S.Ct. 623, 1 L.Ed.2d 639 (1957), which indicates that in deciding whether to compel disclosure by the government, the trial court must balance the competing interests of the defendant with those of the government.

Given the imprecision inherent in applying a balancing test of this kind, we recognize that trial courts must have considerable discretion in deciding when disclosure is appropriate. Where, as here, it is not clear before trial that an informant's testimony will be relevant and helpful to the defense or essential to a fair trial we cannot say, as a matter of law, that there has been an abuse of discretion on the part of the trial court. Roviaro v. United States, supra, 353 U.S. at 60-62, 77 S.Ct. 623.