Can a case proceed to trial on a criminal complaint without a grand jury indictment, and how do preliminary hearings differ?

1. Constitutional baseline: the Fifth Amendment and federal practice

The Fifth Amendment requires prosecution “for a capital, or otherwise infamous crime” to be by grand jury presentment or indictment — and the Justice Manual notes that because federal felonies are “infamous,” an indictment is required unless the defendant waives it ^[1]. Federal Rule 7 implements that rule; the rule and commentary explain that defendants can waive indictment and that an “information” or complaint can substitute when waiver occurs or in narrow statutory exceptions ^{[2] [1]}.

2. How a case can move forward without a full grand jury indictment

Federal prosecutors may initiate arrest and charge by criminal complaint and pursue a preliminary process short of a full grand jury, or the defendant can waive indictment so the government files an information — both can lead to trial settings without a grand jury “true bill” returned by a full federal grand jury ^{[2] [1]}. The recent reporting about the Comey case highlights that departures from ordinary grand jury practice can create legal vulnerability: prosecutors admitted the final indictment was never presented to the full grand jury, a concession courts treat as potentially “highly problematic” ^{[5] [6]}.

3. What a grand jury does and why prosecutors use it

A federal grand jury is a citizen body convened to determine probable cause to indict; Rule 6 sets membership and concurrence requirements, and the DOJ’s grand jury manual stresses the grand jury’s role as an investigatory check that can return an indictment or a “no‑bill” ^{[7] [8]}. Prosecutors often prefer grand juries because proceedings are secret, they can call multiple witnesses and subpoena evidence, and the defense is generally not present to cross‑examine — making indictments relatively easy to obtain in typical practice ^{[4] [9]}.

4. What a preliminary hearing is and how it differs in practice

A preliminary hearing (also called a probable‑cause or “prelim”) is a public, judge‑supervised proceeding where the prosecutor must show probable cause and the defense can attend, cross‑examine prosecution witnesses, and present evidence — and the judge decides whether the case should go forward to trial or to the grand jury (or serve instead of a grand jury in some states) ^{[10] [3]}. Unlike a grand jury, the preliminary hearing is adversarial, the defendant and counsel participate, and the judge — not a panel of citizens — makes the probable‑cause determination ^{[11] [12]}.

5. Strategic tradeoffs: secrecy, evidence, and “preview” of the case

Prosecutors value grand juries for secrecy (protecting witnesses and reputations) and for presenting a one‑sided case to citizens; defense counsel values prelims for the opportunity to test witnesses and see the prosecution’s proof before trial ^{[4] [9]}. Many commentators argue that preliminary hearings are “fairer” because defense counsel can challenge evidence, while grand juries may be more deferential to prosecutors — the “ham sandwich” trope illustrates that imbalance, though some reporting notes recent cases where grand juries refused to indict ^{[9] [13]}.

6. Legal consequences when grand jury procedure is flawed

If a grand jury process is shown to be irregular — for example, if an indictment returned in court was never presented to the full grand jury — courts have treated that as a serious problem that can justify disclosure or motions to dismiss; recent court orders in the Comey matter required DOJ to produce grand jury materials and flagged “profound” missteps in the presentation to jurors ^{[14] [15]}. The Constitution Annotated and precedent emphasize that a valid indictment by a properly constituted grand jury ordinarily suffices to bring a case to trial, and irregularities can threaten that presumption of regularity ^[16].

7. Bottom line and practical advice for readers

If you’re following a case: ask whether the charge is a federal felony (indictment usually required unless waived) and whether prosecutors used a grand jury or a preliminary hearing — because each path changes who sees evidence before trial, what defenses can be tested early, and what procedural challenges are available if prosecutors misstep ^{[1] [3]}. Recent high‑profile litigation shows courts will scrutinize departures from normal grand jury procedure and may order disclosure or sanction flawed practice ^{[5] [14]}. Available sources do not mention state‑by‑state variations in any specific modern case beyond these federal rules, so check local law for precise procedures in non‑federal prosecutions (not found in current reporting).