Walker v. United States, 317 A.3d 388

Alphonso Walker was on trial for a double homicide when, mid-trial, prosecutors introduced inadmissible and prejudicial hearsay suggesting "everyone was saying" Walker committed the murders.
The defense objected, and the trial court agreed the hearsay was impermissible but declared a mistrial over Walker's objection, reasoning this would simply restart the process.
Walker opposed a mistrial without prejudice, explicitly stating he wanted the initial jury to decide his case, as he believed he was on the path to acquittal.
The prosecution and court considered, but rejected, remedies short of mistrial, such as striking the problematic testimony or giving a strong curative instruction.
The trial court’s granting of a mistrial over defense objection raised a double jeopardy (Fifth Amendment) issue: can Walker be retried?
Walker appealed, arguing the double jeopardy clause bars retrial since the mistrial was improperly declared over his objection, absent manifest necessity.

Issue	Walker's Argument	Government's Argument	Held
Whether manifest necessity existed for a mistrial over defense objection	No manifest necessity; wants original jury to proceed; alternatives existed	Error was prejudicial; curative instruction/offending testimony options rejected by defense; mistrial was only way to remedy prejudice	No manifest necessity; alternatives existed; mistrial over objection was error
Whether prosecutorial error can justify mistrial over defense objection	Prosecutorial error should not deprive defendant of jury verdict right; retrial barred	Nature of error was brief, not strategic; mistrial justified to preserve fairness	Prosecutorial error rarely justifies mistrial over objection; defendant retains primary control over proceeding
Availability of reasonable alternatives to mistrial	Curative instruction or striking witness testimony were viable; less drastic measures would suffice	Dismissal with prejudice too severe; weaker remedies insufficient to cure prejudice	Reasonable alternatives were available; mistrial not the only solution
Double Jeopardy Clause bars retrial after mistrial over defense objection	Yes; constitutional right to jury verdict; only extraordinary circumstances allow mistrial over objection	No; mistrial was necessary under circumstances; retrial permissible	Retrial is barred; indictment dismissed under Double Jeopardy Clause

Arizona v. Washington, 434 U.S. 497 (1978) (sets out "manifest necessity" standard for mistrials over defense objection)
United States v. Jorn, 400 U.S. 470 (1971) (defendant's right to continue with original jury in face of error)
United States v. Dinitz, 424 U.S. 600 (1976) (defendant retains primary control over proceeding after prosecutorial or judicial error)
Downum v. United States, 372 U.S. 734 (1963) (government-induced problems rarely justify mistrial over objection)
Illinois v. Somerville, 410 U.S. 458 (1973) (structural problem justifying mistrial is rare; typically requires error before evidence phase)
Price v. Georgia, 398 U.S. 323 (1970) (double jeopardy does not bar retrial after conviction reversed)
Renico v. Lett, 559 U.S. 766 (2010) (deadlocked jury most common, valid ground for mistrial over objection)