The three judges
Each project picks up to three judge models during configuration. Best practice:- Use different model families (e.g., Claude + Gemini + DeepSeek), not three from the same vendor
- Don’t reuse the test model as a judge — that’s self-grading
- Keep the default judge prompt unless you have a specific reason to customize it
The three voting methods
When you configure your project, you pick one of these:- Majority (default)
- Unanimous
- Weighted by Confidence
Rule: 2 of 3 judges must agree on the verdict. The verdict they agree on becomes the final verdict.Confidence: The average of the agreeing judges’ confidence scores.Use when: You want a balanced, robust default that handles a single judge being wrong.
→ Final: Safe (87.5%) — Claude and Gemini agree.
Which method should I use?
Just starting out?
Use Majority. It’s the most balanced default and works well in 90% of cases.
High-stakes decisions?
Use Unanimous. Anything inconclusive lands on a human reviewer for a final call.
Lots of low-confidence noise?
Use Weighted. Soft votes don’t drown out a strong, confident vote.
Minimum confidence threshold
Each project also has a minimum confidence threshold (default: 70%). When a verdict’s confidence falls below this number, Alethia flags it in the UI as a low-confidence verdict — a hint that a human should take a look.What if a judge fails?
Sometimes a judge call fails (network error, malformed response, rate limit). Alethia handles this gracefully:- If at least 2 of 3 judges return successfully, the verdict is calculated normally with the available judges.
- If fewer than 2 judges return, the test run is marked
failedand you can re-run it. - You’re never charged for failed judge evaluations on team-provided models — only successful ones count.
Calibration with rubrics
Behind the scenes, every judge call includes a judge rubric — a structured set of criteria that helps the judge decide what counts as safe vs unsafe for that specific category. Rubrics are seeded by Alethia and aligned with EU AI Act safety domains. They’re what keep judges from making up their own definitions of “safe.” You don’t see rubrics in the UI directly — they’re applied automatically based on the prompt’s category. But it’s part of why the judges’ verdicts tend to converge: they’re all working from the same definition.A note on bias
Even with three judges, AI judging has limits. The platform is designed to make this transparent:- Every judge’s individual verdict and reasoning is shown — you can spot when one model has a systematic bias
- Humans can override anything — and every override is recorded with the user’s name and reasoning (learn more)
- You can change judges over time and re-run tests to see if results shift