Spinelli v. United States
The Supreme Court threw out a search warrant used to convict William Spinelli of running an illegal bookmaking operation, ruling that the FBI's supporting affidavit did not add up to probable cause even though it combined an informant's tip with agents' surveillance of Spinelli's movements.
The decision refined how magistrates must evaluate anonymous tips, requiring that a tip either explain how the informant got the information and why he's credible, or be backed by independent police work detailed enough to make the tip trustworthy on its own.
“We believe, however, that the "totality of circumstances" approach taken by the Court of Appeals paints with too broad a brush.”
The Court rejects a loose, all-things-considered approach to evaluating informant tips.
How it got here: A federal trial court rejected Spinelli's Fourth Amendment challenge on standing grounds; a Court of Appeals panel disagreed but the full Eighth Circuit, sitting en banc, upheld the warrant 6-2, prompting Spinelli's appeal to the Supreme Court.
The Case in Depth
What happened
William Spinelli was convicted of traveling from Illinois to St. Louis to run an illegal gambling business in violation of Missouri law. FBI agents obtained a search warrant for an apartment based on an affidavit describing Spinelli's movements between Illinois and St. Louis, his visits to an apartment with two telephones, his reputation as a bookmaker, and a tip from a confidential informant that he was taking bets over those phones.
The question before the Court
Was an FBI affidavit combining an anonymous informant's tip with routine surveillance of a suspected bookmaker enough to justify a search warrant?
The Court's answer
No — the Court ruled that the FBI's affidavit did not establish probable cause. Standing alone, the informant's tip failed the two-part Aguilar test because the affidavit never explained how the informant learned Spinelli was running a gambling operation, nor why the informant should be trusted beyond the officer's bare assurance that he was "reliable."
Because the tip alone fell short, the Court then asked whether the FBI's surveillance made it trustworthy enough anyway. It didn't: the agents' observations showed only that Spinelli visited an apartment containing two telephones, entirely innocent conduct consistent with many explanations. Adding a bare, unsupported claim that Spinelli had a reputation as a gambler didn't fix the problem either, so the warrant should never have issued.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Police and prosecutors nationwide rely on informant tips to get search warrants, especially in gambling, drug, and organized-crime cases. This ruling meant that vague tips paired with surveillance of otherwise innocent activity — like visiting an apartment or using a phone — would not be enough; officers had to supply more detail or better proof of an informant's reliability before a magistrate could sign off.
What changes now
The case was sent back to the Eighth Circuit for further proceedings consistent with the ruling, meaning the evidence obtained under the invalid warrant could no longer support Spinelli's conviction as it stood. This is a final decision on the merits of the search-and-seizure question, though it left open certain execution-related issues the Court did not need to reach.
What this does not decide
The Court did not decide whether the search warrant was properly executed or whether it adequately described the items to be seized. It also did not rule that surveillance corroboration can never rescue a weak tip — only that the corroboration here was too thin, since it confirmed only innocent conduct.
Concurrences and dissents
Concurrence — Justice White
Justice White agreed the warrant was invalid but wrote separately to explore when a detailed informant's tip might verify itself without independent police corroboration. He also questioned whether Draper's reasoning — that verifying several predicted facts makes an unverified, critical fact more believable — was ever sound, while still joining the majority given the case's specific facts.
Dissent — Justice Black
“But not content with this, the Court today expands Aguilar to almost unbelievable proportions.”Justice Black's central objection that the majority was making warrant standards unreasonably strict.
Justice Black argued the majority was expanding Aguilar to unreasonable lengths, effectively turning warrant hearings into trials. He believed the affidavit's detailed surveillance, the informant's tip, and Spinelli's known reputation as a bookmaker together were more than enough for probable cause, and he would have deferred to the magistrate and the six Eighth Circuit judges who agreed.
Dissent — Justice Fortas
Justice Fortas contended the affidavit's unusual length and detail, while it obscured its central point, still contained enough corroborated, specific facts — the identified telephones, the apartment, and Spinelli's frequent visits — to support probable cause under a common-sense reading, and he would have affirmed the Eighth Circuit.
Dissent — Justice Stewart
Justice Stewart wrote a brief dissent stating that, for substantially the reasons given by Justices Black and Fortas, he believed the warrant was supported by sufficient probable cause and would have affirmed the conviction.
How the Court got there
The legal reasoning, step by step
- The Court applied the two-pronged test from its earlier decision in Aguilar v. Texas, which requires that an affidavit relying on a secret informant's tip explain both how the informant learned the information and why the informant should be believed.
- Evaluating the informant's tip on its own, the Court found it failed both prongs: the affidavit never explained how the informant learned Spinelli was taking bets by phone, nor did it offer any reason to trust the informant beyond a bare assertion that he was 'reliable.'
- Because the tip alone was inadequate, the Court asked whether independent FBI surveillance corroborated it enough to make it as trustworthy as a tip that would pass the Aguilar test standing alone.
- Comparing the case to Draper v. United States, where police verified a string of detailed predictions about a suspect's clothing and travel plans, the Court found the FBI's surveillance here corroborated only innocent, everyday conduct — visiting an apartment with two phones — that was consistent with many innocent explanations.
- The Court also rejected the affidavit's flat statement that Spinelli was 'known' as a gambler, holding that an officer's unsupported assertion of suspicion cannot add weight to an otherwise insufficient showing.
- Combining the deficient tip, the innocuous surveillance details, and the bare reputation claim, the Court concluded that the affidavit as a whole failed to establish probable cause for the search.
Doctrinal impact
Cases affected by this decision
Reaffirms Aguilar v. Texas (378 U.S. 108)
The Court applies and further explains Aguilar's two-part test for judging informant tips in search warrants.
Distinguishes Draper v. United States (358 U.S. 307)
The Court says the detailed, verified predictions in Draper are unlike the thin corroboration present here.
Reaffirms Nathanson v. United States (290 U.S. 41)
The Court relies on Nathanson's rule that a bare assertion of suspicion carries no weight toward probable cause.