On the declaration of a mistrial in Walker v. U.S.

Jamison KoehlerOpinions/Cases

The parties were nine days into a murder trial in Walker v. United States, __ A.3d __ (D.C. 2024), and the case was not going well for the prosecution. 

For example, the defense had successfully impeached one of the government’s witnesses with a prior conviction for perjury, a conviction the prosecutors mistakenly believed would not be admissible.

The same witness also contradicted herself and appeared to be high while testifying.   

The defense successfully impeached the government’s ballistics expert.  The expert conceded that he was merely “eyeballing” the evidence and that his conclusions were not based on “any statistically-derived measurement.”

And it is never easy when your key witness goes by the nickname of “Gangster” and your other witnesses are drug dealers and prostitutes.

All of this was before the government elicited inadmissible hearsay evidence that, going to the core of the case, could have contaminated the jury’s deliberations. 

Specifically, reading from the witness’ testimony before the grand jury, the prosecutor asked her:  “Where was it that night where everyone was saying, ‘your date did this; your date did this.’” 

The defense immediately asked for a mistrial with prejudice.  “With prejudice” would have precluded the government from re-trying the case.

Working from a draft offered by the government, the court tried to fashion curative instructions for the jury. 

However, when the defense refused to accept the proposed fix, the court declared a mistrial, again over defense counsel’s objection:  “All [the declaration of mistrial] does, “ the court stated, “is put everybody back at the starting point” as if “this little gaffe didn’t happen.”

The D.C. Court of Appeals did not agree. 

A mistrial, the Court held, cannot be declared over defense objection unless “manifest necessity” requires it. 

A hung jury is one example of manifest necessary.

The interruption of trials that were underway when the pandemic first hit was another. 

When the prosecution makes a mistake mid-trial, “the defendant must retain primary control over the course to be followed.”  This is true even if the error was sufficient to warrant a mistrial at the defendant’s request:

If the defendant would rather proceed, despite the unfair prejudice the prosecution introduced against him, there is no cogent basis for denying him that right . . . A defendant’s interest in retaining a chosen jury may intensify as the trial proceeds, and where the defendant senses the trial is going well and the factfinder is leaning toward acquittal, stripping him of that jury because of prosecutorial error accords with no sense of fairness or justice.  [Internal citations and quotations omitted.]

In this case, the defense had a number of reasons for wanting to proceed with trial despite potential problems caused by the prosecution’s error. 

For one thing, with the case not going well for the prosecution, the defense did not want to give the government time to fix its case   through another bite of the apple.

For another, the defense had already tipped its hand with respect to its third-party perpetrator defense, a defense it had not revealed pre-trial. 


The trial court quickly concluded that the government’s mistake had been inadvertent; that is, that it had not deliberately tanked the case to give itself another chance to do it again, this time without the mistakes and this time with foreknowledge of the defendant’s strategy. 

Although hesitant to second-guess the trial court, the Court of Appeals appears to have been more skeptical.

And this skepticism was shared by many of my criminal defense lawyer colleagues.

I agree that prosecutors are too rarely held accountable for misconduct, particularly given the enormous stakes for the defendant. 

That said, I have tried two cases against the lead prosecutor in this case.  (After my client was acquitted in one of the cases, she actually came over to the defense table to shake my client’s hand.)

Based on that experience, I would hesitate to ascribe such malfeasance to her, assuming she was the prosecutor who actually introduced the hearsay. 

Instead, I assume that, after 9 days of trial, all of the parties were getting tired, and her question was a mistake, not intentional.