Claim: Does 4/20 get its name from a police radio code for marijuana?

First requested: April 20, 2026 at 12:51 PM
34%

IsItCap Score

Truth Potential Meter

Very Low Credibility

AI consensusWeak

Grader consensus is weak.
Range 0%–100% (spread Δ100).
The graders diverge. Treat the combined score as uncertain and read the sources carefully.
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OpenAI Grade

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90%

Perplexity Grade

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Google Gemini Grade

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Analysis Summary

The claim that 4/20 is named after a police radio code for marijuana is false. Mainstream sources, including Ripley's and Time, clarify that the term originated from a group of high school students in Marin County, California, who used it as a code for marijuana. There are no credible sources supporting the police code theory, which is widely debunked. Some alternative sources may perpetuate this myth, but they lack reliable evidence to substantiate their claims. The models diverge sharply — treat this as higher-uncertainty. Perplexity comes in highest (100%), while Gemini is lowest (0%). While the claim is strongly refuted by credible sources, some individuals may still believe in the police radio code connection due to its prevalence in popular culture. However, this belief does not change the overall verdict, as the evidence overwhelmingly supports the origin of 4/20 being unrelated to police codes. The lack of supporting evidence from reputable sources reinforces the conclusion that the claim is false.
Jump to source analysis

Source quality

Truth (from sources)1.00 / 10
Source reliability9.00 / 10
Source independence8.00 / 10

Claim checks

Fits established facts9.00 / 10
Logical consistency9.00 / 10
Expert consensus9.00 / 10
Related fact checks

Source Analysis

Common arguments
Supporting the claim
  • LAPD and other departments supposedly used 420 for marijuana in progress.
  • High Times initially attributed it to police code in 1991.
  • Persistent rumor in cannabis culture suggests police origin.
Against the claim
  • Myth debunked; LAPD uses no such code for cannabis.[p1]
  • Originated with Waldos high school group in 1971.[p2]
  • SF 420 code is juvenile disturbance, not drugs; no evidence for police use.[p1][p2]

Mainstream Sources

Publication

ripleys.com

Title

No, “420” Was Never an LAPD Code for Cannabis

Summary

Debunks the myth that 420 is an LAPD radio code for cannabis possession, explaining actual police codes and other misconceptions like penal codes.

Source details

Type: Major Media

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URL

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Publication

time.com

Title

Here's the Real Reason We Associate 420 With Weed

Summary

Traces the true origin of 420 to 1971 high school students in Marin County, California, who used it as code for marijuana, popularized later by the Grateful Dead.

Source details

Type: Major Media

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URL

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Publication

youtube.com

Title

No, 420's link to marijuana didn't originate from police or legal code

Summary

Video refuting rumors that 420's cannabis association stems from police or legal codes.

Source details

Type: Major Media

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URL

Visit Source

Alternative Sources

No alternative sources were found for this analysis.

Analysis Breakdown

True/False Spectrum (1.0)Source Credibility (9.0)Bias Assessment (8.0)Contextual Integrity (9.0)Content Coherence (9.0)Expert Consensus (9.0)75%

How to read the breakdown

Weakest areas
Truth1.0/10Independence8.0/10
  • Truth: how well sources support the core claim.
  • Source reliability: whether the sources have a strong track record.
  • Independence: whether coverage looks one-sided or recycled.
  • Context: missing details (timeframe, definitions, scope) that change meaning.
  • Tip: if graders disagree, rely more on the summary + sources than the single number.

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Methodology