Limits on the Right

Limits on the Right

The earlier sections showed the compulsory process guarantee at its strongest. A defendant may bring favorable witnesses to court, may not be denied them by an arbitrary competence rule, and may not have material parts of their testimony excluded by an evidence rule applied mechanically. None of that means the defense may offer any evidence, in any form, at any time. In Rock v. Arkansas the Court acknowledged that the right to present relevant testimony "may, in appropriate cases, bow to accommodate other legitimate interests in the criminal trial process," and then marked the boundary of that bowing: restrictions may not be arbitrary or disproportionate to the purposes they are designed to serve.¹

The standard has two parts, and each answers a different worry. The first part asks whether the rule serves a legitimate interest of the trial process, which concedes that no trial can run without rules about relevance, reliability, and order. The Constitution leaves trial judges wide latitude to exclude evidence that is repetitive, only marginally relevant, or likely to cause harassment, prejudice, or confusion, and States may apply rules that serve fairness and reliability even when the defendant would prefer the evidence admitted.² The second part asks about fit, and it does the subtler work. The State writes the evidence rules, and the prosecution gains whenever defense proof stays out, so a rule that sweeps wider than its stated purpose requires, or that serves no purpose beyond silencing the defense, is the kind a court should be slow to trust. Requiring proportion between rule and purpose lets the legitimate rules stand while exposing those that operate as pretext.

Two decisions show the standard producing opposite results. In Rock the state rule treated a defendant's hypnotically refreshed testimony as always unreliable and gave the trial court no room to consider the particular case. It left the defendant unable to describe the shooting except in the words of the doctor's notes, and the Court held that the rule violated her constitutional right.³ In United States v. Scheffer the Court upheld a military rule that categorically barred polygraph evidence, a rule grounded in the view that polygraph results are of dubious scientific reliability and tend to be unduly influential on the factfinder.⁴ Both rules were categorical, so the label "per se" does not decide the question. What separates the cases is the interest the exclusion touched, because the Court has found an exclusion arbitrary or disproportionate only where it infringed a weighty interest of the accused.⁵ The defendant's own account of the events is the clearest such interest, which fits the observation that the right appears stronger when the defendant is the person who wishes to testify.⁶

The guarantee also has boundaries of timing and subject matter. In Gerstein v. Pugh the Court held that the Fourth Amendment's probable cause determination need not be accompanied by the full set of adversary safeguards, including counsel, confrontation, cross-examination, and compulsory process for witnesses.⁷ The reason is that the sole question at that stage is whether probable cause exists to detain the arrested person, a question traditionally decided by a magistrate in a nonadversary proceeding on hearsay and written testimony, so the trial guarantee does not reach backward into that proceeding.⁸ Washington v. Texas itself cautioned that the clause does not guarantee the defense access to evidence that is privileged, and does not override other non-arbitrary limits on what the defendant may present.⁹

The next section develops the arbitrary-or-disproportionate standard in full, and the two sections after it apply the standard to two different kinds of limit. The first is a restriction on what the defense may put before the jury. Federal Rule 16(d)(2) lets a judge respond to a discovery violation by prohibiting the offending party from introducing the undisclosed evidence.¹⁰ In Taylor v. Illinois the Court recognized that a sanction excluding defense evidence entirely may in some circumstances violate the right to present evidence, yet held that the preclusion order in that case did not.¹¹ The second is a limit on what the defense may reach through process. In Pennsylvania v. Ritchie a defendant charged with abusing his daughter sought, by subpoena, a state protective agency's confidential file. The Court declined to treat the Compulsory Process Clause as a source of pretrial discovery, and it measured his claim under due process, which required only that the trial court review the file in camera for evidence that was both exculpatory and material.¹²

The two applications share one question. The clause protects the defendant's ability to present a defense, but the trial has legitimate interests of its own in orderly discovery, reliable evidence, and protected confidences. A restriction survives when it serves one of those interests in proportion, and it fails when it defeats the defense for no good reason. Students lose this issue when they treat a categorical exclusion as unconstitutional merely because it is categorical, when the Court's inquiry turns on the weight of the accused's interest and the fit between the rule and its purpose.¹³

Arbitrary or Disproportionate Test

The right to present a defense gives way to other legitimate interests of the trial, so a court needs a working test for deciding which restrictions are permissible. The Court has supplied one with two connected parts. A rule that keeps defense evidence out violates the right only if it is "arbitrary or disproportionate" to the purposes it was designed to serve, and the Court has found exclusions unconstitutional on that ground only where they infringed a "weighty interest of the accused."¹⁵ Each part asks something different. The first compares the rule with its own stated purpose, so it is a question about fit. The second looks at what the exclusion takes from the defendant, so it is a question about stakes.

The two parts exist for different reasons. The stakes requirement is functional. In a single trial the judge makes dozens, sometimes hundreds, of rulings on admissibility, and the Constitution leaves the judge wide latitude to exclude evidence that is repetitive, only marginally relevant, or likely to cause harassment, prejudice, or confusion.¹⁶ If every exclusion that hurt the defense raised a constitutional claim, routine evidence rulings would turn into federal questions, and requiring a weighty interest keeps minor limits out of that category. The fit requirement answers an incentive problem. The state writes the evidence rules, and the prosecution gains whenever defense proof stays out, so a rule's stated purpose is the only thing separating a legitimate screen from a rule that merely disables the defense. Asking whether the means actually match that purpose puts the state's justification to a direct test, and it leaves standing the rules that serve fairness and reliability even when a defendant would prefer the evidence admitted.¹⁷

A categorical rule can fit its purpose well, and the polygraph ban shows how. In United States v. Scheffer an airman tried by court-martial for using methamphetamine offered the results of a polygraph examination indicating that he had not knowingly used the drug, and the military judge excluded them under Military Rule of Evidence 707, which bars polygraph evidence outright.¹⁸ The rule rests on the view that polygraph evidence is of dubious scientific reliability and tends to be unduly influential on the factfinder. When the Court of Appeals for the Armed Forces held that the ban violated the right to present a defense, the Supreme Court reversed.¹⁹ The ban matches its rationale, which is why a flat rule can stand. If polygraph results as a class are doubtful, excluding the class removes evidence the state has real reason to distrust, and no case-by-case sorting is needed to serve the purpose. Because the category itself is the source of the doubt, a flat exclusion does not catch reliable evidence by accident. Evenhanded exclusionary rules of this kind are constitutional as applied to a defendant so long as they are not arbitrary or disproportionate to a legitimate interest such as reliability.²⁰

Reliability was also the stated purpose in Rock v. Arkansas, and that shared purpose makes the case a clean contrast. The Arkansas courts treated a defendant's hypnotically refreshed testimony as always unreliable and excluded it in every case, so the rule operated without regard to the reasons for the hypnosis, the circumstances under which it took place, or any independent verification of what it produced.²¹ The category was therefore a poor proxy for the risk the state invoked. A defendant whose memory of the day was confirmed by other witnesses was excluded exactly as a defendant whose account rested on nothing but the hypnosis session, and the rule had no means of telling them apart. The cost to the petitioner was concrete: the rule virtually prevented her from describing the events of the day of the shooting, and she could describe the shooting itself only in the words of the doctor's notes.²² The Court held that she had a constitutional right to tell her story despite the state's rule.²³ The same purpose that sustains the polygraph ban therefore condemned the hypnosis rule, because the polygraph category is itself doubtful while the hypnosis category swept in testimony without asking whether it was doubtful in the case at hand.

The far end of the range is the exclusion for which the state offers no justification at all. In Crane v. Kentucky the Kentucky courts foreclosed a defendant's effort to introduce evidence about the environment in which police obtained his confession, and the Court observed that neither the state court nor the prosecution had advanced any rational justification for the wholesale exclusion of that body of potentially exculpatory evidence.²⁴ Excluding competent, reliable evidence that is central to the defense, with no valid state justification, deprives the defendant of the meaningful opportunity to present a complete defense.²⁵ The three decisions therefore mark three positions on the fit question. Crane involved a rule with no justification at all, Scheffer a rule whose reach matches its justification, and Rock a rule that has a justification but overshoots it.

The second part of the test keeps the first from reaching every imperfect rule. A rule can fit its purpose poorly and still barely touch the defense, as a limit on cumulative or marginal evidence might, and the Court has located violations only where a weighty interest of the accused was infringed.²⁶ Both conditions must be met, so a strong argument about fit still fails if the excluded evidence was peripheral. A rule that strikes at the center of the defense can satisfy the stakes requirement even when the interest is not the defendant's own testimony. In Holmes v. South Carolina the Court held that excluding third-party-guilt evidence, on the ground that as a matter of law it could not raise a reasonable inference of the defendant's innocence when the prosecution had scientific forensic evidence of guilt, denied the defendant a fair trial.²⁷ The exclusion blocked the defense's alternative account of who committed the crime, which is the kind of interest the second requirement protects.

The common error is to accept the state's reliability label at face value, when the inquiry asks whether the rule fits that purpose. Reliability explained both the polygraph ban and the hypnosis rule, and only one of them stood, because categories differ in how closely they track the risk the state invokes.²⁸

Discovery Sanctions

Discovery rules let each side learn what the other will offer and prepare to test it, and the rules mean little unless a court can penalize a violation. Rule 16(d)(2) gives a trial court several responses to a discovery violation, from ordering the discovery or granting a continuance to prohibiting the offending party from introducing the undisclosed evidence.³⁴ The last response collides with the right to present witnesses, because preclusion keeps a defense witness off the stand even though the defendant has secured the witness's attendance. In Taylor v. Illinois the Court asked whether the Compulsory Process Clause is violated when a trial court excludes the testimony of a defense witness as a sanction for the defendant's failure to comply with a discovery request or order.³⁵ It answered by rejecting two opposite positions, and the reason for each rejection is what the case teaches.

The State's position was that preclusion as a discovery sanction raises no compulsory process question at all. It pointed to the plain language of the clause, to historical evidence that the clause was meant to give defendants a subpoena power they lacked at common law, to scholarly comment, and to a brief excerpt of legislative history.³⁶ On that reading the clause guarantees only that the defense can get a witness to court, so whether the witness may then testify lies outside it. The Court responded that it had consistently given the clause the broader reading reflected in contemporaneous state constitutional provisions. It also drew on Pennsylvania v. Ritchie for the minimum content of the right, which includes the government's assistance in compelling favorable witnesses to attend and the right to put before a jury evidence that might influence the determination of guilt.³⁷

The reason for the broader reading comes from the adversary system. A right to compel a witness's presence could not protect the integrity of that system if it did not also include the right to have the witness's testimony heard by the factfinder, and Washington v. Texas described the right to offer witnesses as the right to present the defendant's version of the facts to the jury so it may decide where the truth lies.³⁸ A separate dissenting opinion accepted the same premise on a similar ground, observing that a right to subpoena defense witnesses would be hollow if the government could then refuse to let those witnesses testify.³⁹ The Court therefore refused to accept that the right can never be offended by a sanction that entirely excludes the testimony of a material defense witness.⁴⁰

The defendant's position was the mirror image of the State's: the clause, in this view, creates an absolute bar to precluding the testimony of a surprise witness. The Court called that position just as extreme and just as unacceptable as the State's.⁴¹ The accused has no unfettered right to offer testimony that is incompetent, privileged, or otherwise inadmissible under standard rules of evidence, and the Court described the clause as providing "an effective weapon, but it is a weapon that cannot be used irresponsibly."⁴² A disclosure order is part of what keeps the weapon responsible. If the defense could ignore the order and still call the undisclosed witness, the prosecution would face testimony it had no chance to investigate or answer, and an adversary system that depends on developing all the relevant facts would be working from a partial presentation.⁴³

As the dissent frames the result, the Court held that a trial judge may constitutionally preclude a criminal defendant from introducing a witness's testimony as a sanction for the defendant's failure to comply with a discovery order.⁴⁴ That is the pole where the rule applies: the defense did not disclose a witness as ordered, the trial court precluded the witness's testimony, and the Court held that the clause does not categorically forbid that sanction.⁴⁵ The holding permits preclusion without making it routine, because rejecting the State's position keeps the clause available as a limit on how the sanction is used.

The dissent shows the competing view. It describes the majority as stressing the importance of discovery rules and the need to deter violations, and as suggesting that the possibility of fabrication supported the exclusion.⁴⁶ Justice Brennan, joined by Justice Marshall, accepted that the right is not absolute and that discovery rules serve important purposes. He argued, however, that excluding a witness is a drastic sanction for the most extreme circumstances, because the purposes of discovery rules can be served by sanctions that leave the evidence in, such as a continuance or an instruction that the defense violated the rules.⁴⁷ On the facts as the dissent saw them, the exclusion took away the petitioner's only eyewitness, the State's case rested on two witnesses with strong motives to lie, and nothing in the record showed coaching or fabrication, since the proposed testimony matched a statement given to the police shortly after the incident.⁴⁸ The majority and the dissent thus shared the premise that the clause applies and is not absolute, and they parted on how readily preclusion is justified when a lesser sanction is available. Only the majority's view is law, but the dissent's considerations (the importance of the witness, the availability of lesser sanctions, and the evidence of fabrication) are the points a defense lawyer would press to argue that a particular sanction went too far.

Two companion authorities confirm that the clause does not exempt the defense from the court's own processes. In United States v. Nobles the defense proposed to call an investigator to impeach the identification testimony of the prosecution's eyewitnesses, and the trial court imposed a condition requiring disclosure of the relevant portions of the investigator's report.⁴⁹ The Court reasoned that the judiciary's compulsory processes stand available to require the presentation of evidence, and it held that the Fifth Amendment did not bar the order, because the order reached only statements of third parties who were available to both sides and no communication from the defendant.⁵⁰ The same logic supports sanctions for ignoring a disclosure rule. Evenhanded exclusionary rules are constitutional as applied to the defendant when they are not arbitrary or disproportionate to a legitimate interest, and ensuring defense compliance with reasonable discovery rules is such an interest. Michigan v. Lucas accordingly upheld the exclusion, from a rape trial, of defense evidence of prior consensual sex between the defendant and the victim, because the defense had not given the pretrial notice that the rape shield law's disclosure provision required.⁵¹

Students most often lose this issue by adopting one of the two extreme positions the Court rejected, either by treating a discovery sanction as outside the clause altogether or by treating the clause as a bar to preclusion in every case. The first position overlooks that the right to present witnesses is an essential attribute of the adversary system. The second overlooks that the accused may not use the clause irresponsibly.⁵²

Access to Government Files

The earlier sections here assumed that the defendant knows who the witness is and that the state either helps or hinders that witness's appearance. A different kind of claim arises before that stage, when the defendant does not know what the state's records contain and asks a court to open them in the hope of finding something useful. Pennsylvania v. Ritchie presented that claim. Ritchie, charged with abusing his daughter, sought the confidential file of a children-and-youth-services agency (CYS), and a Pennsylvania statute made the agency's reports confidential, releasing them only to a short list of recipients that included a court acting under a court order.⁵⁴ He argued that withholding the file kept him from learning the names of witnesses in his favor and from seeing other evidence the file might hold.⁵⁵ The Pennsylvania Supreme Court had suggested that the Compulsory Process Clause includes the State's help in uncovering arguably useful information even when a state-created restriction, here the confidentiality of the files, stands in the way, so the Supreme Court had to decide whether the clause reaches that far.⁵⁶

The Court opened by noting how little it had said about the clause. The first and most celebrated analysis came from a Virginia federal court in 1807, during the treason and misdemeanor trials of Aaron Burr, when Chief Justice Marshall, presiding as trial judge, ruled that Burr's compulsory process rights entitled him to serve a subpoena on President Jefferson requesting allegedly incriminating evidence.⁵⁷ The clause then played little part in the Court's decisions for roughly 160 years, and the more recent cases have stated its specific content only in outline. At a minimum, criminal defendants have the right to the government's assistance in compelling the attendance of favorable witnesses at trial and the right to put before a jury evidence that might influence the determination of guilt.⁵⁸ Both rights operate at trial: one gets a witness into the courtroom, and the other lets the evidence reach the factfinder. Neither describes a right to have the state help the defendant find out, before trial, what witnesses or evidence exist, which is why Ritchie's claim sat at the edge of the clause's established content.

The Court next observed that it had never squarely held that the clause guarantees a right to discover the identity of witnesses or to require the government to produce exculpatory evidence, although it noted that United States v. Nixon suggests the clause may require the production of evidence.⁵⁹ Claims like Ritchie's had traditionally been evaluated under the broader protections of the Fourteenth Amendment's Due Process Clause, as in Brady v. Maryland and United States v. Bagley.⁶⁰ Because the Sixth Amendment's application to this kind of case was unsettled, and because the due process precedents on the fundamental fairness of trials supply a clear framework, the Court analyzed the claim under due process.⁶¹ It concluded that compulsory process provides no greater protection in this area than due process does.⁶² The Confrontation Clause theory Ritchie also advanced, which concerned his ability to cross-examine trial witnesses, was rejected by a plurality on separate grounds and is not the subject here.⁶³ How due process governs what the prosecution must disclose belongs to a separate reading on prosecution disclosure duties, and Ritchie matters here because it sends this kind of claim there.

The holding is narrower than it is sometimes reported. The common error is to say that the clause has nothing to do with evidence in government hands, when the Court held only that compulsory process gave Ritchie no greater protection than due process on these facts. It expressly declined to decide whether and how the guarantees of the Compulsory Process Clause otherwise differ from those of the Fourteenth Amendment.⁶⁴ A later court can therefore still ask whether the clause adds something in a different setting, but a defendant relying on Ritchie itself gets the due process standard.

The reason for routing the claim to due process shows in what each guarantee is built to do. The clause speaks of obtaining witnesses in the defendant's favor, so its machinery of subpoenas, attendance, and a chance to be heard presupposes a witness or item the defendant can point to. A request to examine an agency's file is a request to investigate, and the defendant cannot name what is sought because the purpose of the request is to learn whether anything useful exists. Due process asks a more flexible question about fundamental fairness, weighing the circumstances and burdens case by case, and the Court had already built a body of standards under it for exculpatory-evidence claims.⁶⁵ Using that framework also avoids stretching the clause into a general discovery right that the Court's own precedents did not require.⁶⁶

A contrasting case shows what the clause does cover directly. In Washington v. Texas Texas statutes barred an alleged accomplice from testifying for the defendant, who wanted the accomplice to say that the defendant tried to prevent the homicide and fled before the accomplice fired the fatal shot, and the Court held that the statute arbitrarily denied the defendant the right to present relevant and material evidence.⁶⁷ The clause applied directly there because the state kept a known witness from being heard, whereas Ritchie sought help in finding out whether any useful witness or evidence existed. Washington itself cautioned that the clause does not guarantee defense access to privileged evidence or override other non-arbitrary limits on the defense, so even a witness-based claim has boundaries.⁶⁸