Merlise achieves breakthrough results on SciFact-Open
Merlise
Editorial · Failure mode

The claim had already been checked. It came back anyway.

20264 min read

A claim that cancerous tumors are the body's way of storing toxins, and that cancer itself is a healing response, keeps circulating in slightly different phrasing, a few months apart. Fact checking organizations have addressed it more than once already. Somebody did catch it the first time. Catching it once simply did not stop it from coming back.

The wording changed. The underlying claim, already checked and found false, did not.

Fact checking needs a memory

A claim does not become new just because it shows up in a new video, a new post, or a new caption. If the underlying assertion has already been checked, the honest response is to connect the new instance to the existing record, not to treat a recurrence as a fresh investigation.

Exact text matching would miss this entirely, so Merlise combines semantic similarity with source authority instead. "Cancer is a bag of toxins" and "tumors are how the body heals itself" read as different sentences and describe the same underlying claim. Catching that means understanding meaning, not counting matching words.

Why this reaches beyond one health claim

Zombie claims are not unique to health misinformation. A false statistic, a fabricated quote, or a misleading chart can resurface years after its first debunking, in politics, in finance, in science reporting. A team checking claims does not want to rebuild context from nothing whenever something old comes back wearing new language.

Merlise's answer is a form of institutional memory: when a claim resurfaces, show the current instance next to the prior checks, the authoritative sources behind them, and whether anything about the new version is actually different. Health content deserves extra care here. Merlise points to the resolving authority and explains the risk instead of offering medical judgment of its own.

The evidence ledger

The same claim by claim view the product shows on a live document, built from this case.

VERIFICATION LEDGERRecurring claim, matched to prior checks
"Tumors are the body's way of storing and healing from toxins."Relational
4%
Matches a claim already checked and rated false; recurring with no new supporting evidence.Refuted
Prior fact checks

How it resolves

Same claim, three different sentences
YearWording usedStatus
2021"Cancer is the body storing toxins"Rated false
2023"Tumors are a bag holding poisons"Matched to 2021 rating
2026"Tumors are the body's way of healing from toxins"Matched to 2021 rating

The resolving record

An established fact checking organization documented the recurrence directly, linking the current version of the claim to its prior debunks and to relevant health authority guidance.

Full Fact, recurring claim tracker