AI Control — Safety Despite Subversion
Control stops asking whether the strong model is trustworthy and asks what you can do if it isn't. Greenblatt, Shlegeris, Sachan, and Roger (Redwood Research, arXiv:2312.06942, ICML 2024) show that with a weaker trusted model and a small human audit budget, Trusted Editing Pareto-dominates Untrusted Monitoring on a code-backdoor task. Safety here means the probability that an adversarially chosen U cannot cause a concrete unacceptable outcome, measured under red-team pressure.
Learning Objectives
- Define the AI Control threat model: untrusted strong model U, trusted weaker model T, trusted human budget H.
- Describe the Trusted Editing protocol and why it Pareto-dominates Untrusted Monitoring on the ICML 2024 code-backdoor task.
- Explain the difference between alignment (U is trustworthy) and control (U is not trustworthy and we are safe anyway).
- State the three limits of control: humans do not scale, trusted weak models eventually lag, control does not produce trustworthy strong models.
The Problem
Lessons 7-9 establish that a frontier model may be deceptively aligned, scheming, or faking alignment. That changes the safety question. Instead of asking whether the model is trustworthy, ask whether you can get useful work out of it without giving it a chance to cause an unacceptable outcome. This is the control problem, and it is built like classical security: assume a worst-case adversary, design a protocol, and measure how often the adversary wins under red-team pressure.
The Concept
The threat model
Control assumes three resources:
- U is the untrusted strong model. It is capable and possibly adversarial (the evaluation treats it as if it were).
- T is the trusted weaker model. It is less capable, but known not to be adversarial.
- H is trusted human labor. The budget is small and does not scale.
The system has to produce useful output using U. The adversary wants a concrete unacceptable outcome, such as a backdoor in the shipped code, while still doing enough legitimate work to pass the usefulness thresholds.
Control gives up on trusting U and asks which protocols keep you safe anyway.
The ICML 2024 backdoor task
Prompts are competition-level coding problems. U produces a candidate solution, and a hidden oracle flags whether it contains a backdoor (a specific input that makes the code produce a wrong output). The red team controls U and can see all protocol internals. The protocol has to maximize the solved-problem rate while keeping the backdoor-shipping rate below a threshold.
Four protocols compared
- Baseline: ship U's output directly. Usefulness is maxed and safety is minimal.
- Upfront auditing: use H on all outputs. Safety is maxed, but the budget runs out quickly.
- Untrusted Monitoring: a second instance of U scores the first instance's output, and H audits what gets flagged. The risk is that the two instances can collude.
- Trusted Editing: T edits U's output on every query. If T is not confident, the output goes to H.
Greenblatt et al. find that Trusted Editing Pareto-dominates Untrusted Monitoring: higher usefulness at every safety level.
Why Trusted Editing wins
Untrusted Monitoring only works if U's second instance cannot coordinate with the first. Collusion can happen through steganographic cues or shared training priors, so the protocol has to spend budget on collusion-resistance (paraphrasing, obfuscation), and that reduces the monitor's signal. Trusted Editing sidesteps the problem because T is trusted, so any edit T proposes is not adversarial by assumption. The price is capability. T is weaker, so it may over-reject or miss a subtle backdoor.
The four protocol axes
- Which role U plays: producer only, monitor, or both.
- Which role T plays: editor, monitor, or resampler.
- How H is allocated: uniform audit, random audit, or flag-directed audit.
- How much compute the protocol spends on collusion-resistance.
Alignment vs control
- Alignment asks "is U safe to trust?" Lessons 2, 4, 5, 6, 7, 8, and 9 all bear on this.
- Control asks "can we use U safely without trusting it?" This lesson covers that.
Alignment is a property of the model. Control is a property of the deployment protocol. Control does not produce aligned models. It produces safe use of possibly-unaligned ones, and you need both agendas.
Three fundamental limits
- Humans do not scale. The H budget is capped by how many people are willing to audit hard AI outputs.
- Trusted weak models eventually lag. When T is far weaker than U, T's editing signal turns into noise.
- Control is not alignment. A protocol that works at ASL-3 (Lesson 18) may not work at ASL-4, because if U can manipulate T or reason about H's audit distribution, control fails.
The 2025 development
UK AISI and Redwood collaborate on Control Safety Cases (metr.org / redwoodresearch.org 2025). A control safety case argues that under worst-case assumptions about U, the protocol bounds the probability of an unacceptable outcome. Safety cases (Lesson 18) inherit the control frame.
Where this fits in Phase 18
Lessons 6-9 describe the threat: deception is possible. This lesson describes the defensive paradigm for the case where the threat is real. Lesson 11 covers the complementary offensive paradigm, making U trustworthy through scalable oversight.
Use It
code/main.py simulates the four protocols on a toy backdoor task. U produces outputs and a fraction are backdoored (the red-team policy). T approves or edits, and H is called on a budget. The script sweeps the backdoor rate and the collusion parameter, with the H budget fixed at 0.10. To sweep the budget as well, change h_budget. You get the shape of the Pareto frontier in Greenblatt et al. 2024 Figure 2, not the numbers. The toy counts a shipped backdoor as not useful, so Baseline's usefulness lands below Trusted Editing's here, unlike the framing in The Concept where Baseline maxes usefulness.
Ship It
This lesson produces outputs/skill-control-protocol-audit.md. Give it a deployment protocol description and it identifies the U / T / H roles, names the collusion vectors, and estimates where the protocol sits on the usefulness-safety frontier under red-team pressure.
I would read the numbers in main.py as a statement of the toy's assumptions, and the ranking only as far as those assumptions go. T gets is_backdoor handed to it. It removes a backdoor with probability t_skill, which is 0.7, and rejects 5% of benign outputs. It does not read any code. The monitor is the same kind of coin flip: it flags 80% of backdoors unless collusion suppresses the flag, and it falsely flags 5% of benign outputs. So the simulation shows how a protocol behaves given those probabilities, and says nothing about whether a real T can hit 0.7.
The collusion sweep is where I'd spend my time. It runs collusion at 0.0, 0.20, 0.50, and 0.80 with everything else fixed, so you can watch the monitor's safety signal erode as that one parameter climbs. The trend is noisy below 0.20, where the budget is spent on whichever outputs arrive first, but from 0.20 up the backdoor-ship rate rises (0.033, 0.064, 0.087 in the seeded run). Trusted Editing has no such parameter, and that absence is the whole argument. It also means the comparison is partly decided by construction. I'd want to see Trusted Editing hold up at a lower t_skill before trusting the ranking.
One more detail. The upfront branch audits the first outputs until the budget is spent and ships the rest unchecked, so at a 0.10 budget it falls short of the maxed safety described above. Audit order in a real deployment is a design choice, and exercise 3 touches on it by asking how to hide the audit distribution from U.
Exercises
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Run
code/main.py. Reproduce the usefulness-safety frontier for Trusted Editing vs Untrusted Monitoring. Identify the budget regime in which Untrusted Monitoring's collusion assumption becomes pivotal. -
Add a new protocol: "T resamples with low temperature, then U edits T's output." Measure its position on the frontier. Why does this fail more catastrophically than Trusted Editing?
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The 2024 paper assumes U can see the protocol. Design a protocol that hides from U which outputs are being audited. What does this protocol require from the deployment infrastructure?
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Read Greenblatt et al. 2024 Section 7 (collusion). Propose a collusion-resistance measure and explain its expected usefulness cost.
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Articulate a control safety case for a deployment that uses U = GPT-4-class, T = GPT-3.5-class, H = 1% of outputs audited. Identify the single strongest assumption the case depends on.
Key Terms
| Term | What people say | What it actually means |
|---|---|---|
| AI Control | "safety under subversion" | Protocol design that bounds unacceptable outcomes under a worst-case U |
| Untrusted model (U) | "the strong model" | The capable model we want to extract work from but do not trust |
| Trusted model (T) | "the weak model" | A weaker model, known not to be adversarial, used as editor/monitor |
| Trusted human (H) | "the audit budget" | Bounded expert labor; expensive; the ground-truth signal |
| Trusted Editing | "T edits U" | Protocol where T is the gate on U's outputs; H called on ambiguous outputs |
| Untrusted Monitoring | "U monitors U" | Protocol where a second U instance scores outputs; collusion-resistant only with extra investment |
| Control safety case | "the formal argument" | Written argument that a protocol bounds the adversary's success under worst-case U |
Further Reading
- Greenblatt, Shlegeris, Sachan, Roger: AI Control (arXiv:2312.06942), the canonical ICML 2024 paper
- Redwood Research: Recent AI Control papers index, 2024-2025 follow-ups
- UK AISI + METR: Control safety cases, operationalization for frontier labs
- Hubinger et al.: Sleeper Agents (Lesson 7, arXiv:2401.05566), the threat model control assumes
Code
- main.py (python, 138 lines)