Treat the assistant as a delegated action path, not as a separate identity with open-ended authority. Limit it to explicitly approved signature actions, bind every operation to the authenticated user's permissions, and preserve an audit trail that proves who initiated the transaction and under what conditions.
How to govern an AI assistant that can sign?
An AI assistant that can initiate contract signatures should be governed as a bounded delegation mechanism, not as a free-standing actor. The key control question is whether the assistant can only execute a narrowly approved signature path, with every action tied to an authenticated human user's authority, policy conditions, and evidence trail. Without that structure, the assistant becomes a broad signing channel rather than a workflow aid.
That distinction matters because contract signature is a high-impact action with legal, financial, and compliance consequences. Governance should therefore focus on who may trigger the action, which contracts it may touch, what approvals must already exist, and how the system records the full chain of custody for the transaction.
For AI assistants used in enterprise workflows, the practical model is closer to constrained delegation than autonomous authority. NHIMG's Agentic AI Security Policy Template is a useful starting point because it treats registration, identity, access, oversight, tools, monitoring and retirement as governance questions, not just technical settings. If the assistant can reach signing tools, the approval boundary and retirement process need to be explicit before rollout.
What authority should the assistant actually have?
The assistant should inherit the initiating user's permissions for that transaction, but only inside an explicitly defined signing scope. That means the system should not allow the assistant to decide on its own that a signature is appropriate, nor should it hold open-ended authority to sign on behalf of an organisation just because a user is logged in.
In practice, the safest design is to separate drafting, review, approval and execution. The assistant may prepare the packet, surface required fields, or route the request, but signature execution should only occur after the user has completed the required human decision and the contract falls within the approved policy set. This is where least privilege is operationalised for an AI-assisted workflow.
For teams building broader agent governance, NHIMG's Agentic AI Security Guide provides the right mental model for treating tool access as a constrained action surface, and NHIMG's AI Agent Identity Security Buyer's Guide helps teams evaluate the controls that bind an agent's actions to a legitimate user context.
When the assistant must interact with signature systems through APIs or service integrations, governance should also account for endpoint-level authorization. NIST SP 800-53 Rev. 5, especially IA-5 and AC-6, aligns well with making signatures conditional on controlled credential use and least privilege.
What evidence and controls should survive audit?
A defensible signing workflow should preserve evidence that answers four questions: who initiated the transaction, what contract was presented, what policy condition allowed the action, and what exactly the assistant did before the signature was executed. If any of those are missing, the organisation may know that a signature happened but not whether it was properly authorised.
The audit trail should therefore capture the authenticated human identity, the assistant instance or workflow identifier, the approval state, the contract version, the timestamp, and any exception or escalation that occurred. That record is what allows security, legal and internal audit teams to reconstruct the decision without relying on the assistant's own summary.
For external assurance and policy alignment, the EU AI Act and NIST AI RMF are relevant because they frame accountability, oversight and traceability as governance obligations for AI-enabled systems. NIST's NIST AI Risk Management Framework supports the control objective, and the European Commission's EU AI Act regulatory framework is the better reference when the assistant's behaviour affects regulated workflows or high-impact decisions.
Risk and Threat Considerations
When an assistant can initiate signatures, the main risk is authority expansion through misuse, misconfiguration or prompt-driven manipulation. A weak design can let the assistant sign outside the intended contract class, bypass a required approval, or reuse a user's authority in a context the user never actually approved.
Failure mechanism: The workflow collapses when the assistant is treated as if it had durable signing authority instead of narrowly delegated, session-bound authority. In that condition, compromised prompts, connector abuse or overly broad permissions can turn a convenience feature into an unreviewed execution path.
Impact: Incorrect or unauthorised signatures can create legal exposure, financial commitments, repudiation disputes and evidence problems. The organisation may also lose the ability to prove that the transaction was initiated under the right conditions and by the right human actor.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Agentic AI Top 10 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | The assistant's signing power hinges on delegated authority and user-bound permissions. |
| Recommendation — Bind signing actions to authenticated user authority and deny any open-ended agent privilege. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Signing workflows depend on controlling the credentials or tokens that authorize execution. |
| AC-6 — Least Privilege | The assistant should only execute the narrow signing actions the user is allowed to approve. | |
| AU-2 — Event Logging | Auditability is essential for proving who initiated and conditioned the signature. | |
| Recommendation — Manage signing credentials so every approved action is traceable to a controlled authenticator. Restrict the assistant to the minimum signing permissions needed for the transaction. Log each signature initiation, approval state and contract version for later review. | ||
Practitioner Guidance
What to verify: Confirm that the assistant cannot sign unless the initiating user is authenticated, the contract is within an approved policy scope, and the signature request is bound to a specific transaction rather than a general capability. If the workflow cannot demonstrate all three, it is too permissive.
Decision rule: If the assistant can materially change the legal state of a contract, require explicit approval gates, human ownership of the request, and a transaction log that is readable by audit and legal teams. If it can only prepare or route documents, keep it out of the execution path entirely.
Practitioner takeaway: The right control objective is not "can the assistant sign", it is "can the assistant only carry out a signature the human was already authorised and expected to make, with evidence strong enough to defend the transaction later."
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on October 21, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org