The citation judge for legal AI

Kingsfield rules.

ACCEPT, REJECT, or INCONCLUSIVE
On every citation your legal AI produces.

Kingsfield Active Platforms:

  • Microsoft Word
  • Kingsfield web portal
  • Any MCP compliant AI platform

Runs alongside the legal AI your firm already pays for

Harvey CoCounsel Lexis+ AI Westlaw Precision Spellbook Hebbia Robin AI EvenUp Paxton Sqyro
How it works

The layer that checks
your AI's citations.

Kingsfield does not write your brief. It rules on citations your brief depends on.
Verdicts are derived from compiled US primary-law corpus, delivered over MCP.

Per citation

Independent adjudication

Legal AI LLM models draft from training data then validate their own work. Self-check is not verification. Kingsfield rules from US primary-law corpus locked in his own bespoke database.

Fail-closed

PII never reaches Kingsfield

Client identifiers are pre-tokenized and must clear two firewalls before the judge sees your draft. A fail-closed at your browser and a second at the judge's door.

Signed

A verdict you can defend

Every ruling is a signed Audit Capsule: SHA3-256 hash chain plus an Ed25519 signature, roughly 4 KB, PII-free. It travels with the brief.

Coverage

Federal and state law, growing daily

Federal law plus 19 states are live today — AK, CA, DE, FL, IL, NV, NY, PA, TX, VT, WY, LA, MS, GA, RI, MA, CT, NH, ME — with new state corpora going live continuously and all 50 on the way. A cite outside the covered corpus is marked not checked, never failed.

BYO-LLM · MCP

Keep your stack

Harvey, CoCounsel, Lexis+, Westlaw, Claude, GPT. Whatever drafts your work, Kingsfield reaches it as an MCP server. You keep your keys and your workflow.

Good law

Still good law

A real case can still be overruled. Kingsfield checks whether the authority is current, not just whether it once existed, and flags cites that no longer hold.

Kingsfield Citation Verdicts

700 US court-sanctioned AI citation errors, Kingsfield ruled 696 correctly.

Actual Case Verdict Demo kingsfield.ai · adjudicate() · MCP

Scroll each Kingsfield verdict

25 real AI hallucinated cases. Click to see how Kingsfield's ruling compared to the actual case judge's verdict. Click through to see the full case details.

§

The verdict appears here. Pick a citation on the left to watch Kingsfield rule.

Audit CapsuleCPS-0000
REJECT
AI tool
Citation
Proposition
Ruling
Read the full case write-up
Ed25519 · SHA3-256 chain 0x0000…0000
Trust & Privacy

Architecturally Designed
and Engineered Structure

Not generic third-party attestations

SOC2
Hosted · kingsfield.ai
Kingsfield
MCP server · BYO-LLM · per draft

Why does Kingsfield not toe the line of recognized general frameworks to ensure compliance as virtually all legal SaaS platforms do? Certainly that would be the easy route to follow as our search for client sales progresses. But is it more or less honorable to do so? Definitely less, in our considered opinion. Audit attestation providers are fraught with dubious practices, and Kingsfield chose, for better or worse, to take the higher path. We hide nothing. Our architectural design is documented and available to any potential client under NDA.

PII firewallPer citationPer quotePer propositionGood lawCapsule signed
+
Local · your machine
PII Tokenizer
Browser shield, free.

What is tokenizing and why is it needed? The WalkerNash engineering team designed and engineered tokenizers to protect Kingsfield first, and lawyers and law firms second, from leaked sensitive client data. Kingsfield never sees non-tokenized PII by design, and never stores or retains content, which other vendors also claim but cannot structurally prove. Legal counsel face even greater liability under Model Rule 1.6 when they hand over client PII to SaaS vendors who profess but cannot show proof that sensitive data can never leak.

Forward tokenizerEgress gate31-pattern scanFree shield
Tokenized PII Visualized

Toggle to see what leaves your machine. CLIENT_0001 is what Kingsfield rules on; it never sees the client, and the verdict capsule comes back PII-free, so nothing needs mapping back.

Pricing

Pay only for accepted cites.

You pay only for the citations that check out, priced in tiers by how many pass. A draft full of fabrications costs the $10 floor and nothing more: we never bill you for catching a fake. We only get paid when your cites are good, so we have no reason to over-reject. No subscriptions, no seats, no enterprise discounts: the solo and the national firm pay the same published rate. Start with $50 in free credit, then bill each ruling to your client as a recoverable cost.

Pay as you go
Every licensed attorney, the same rate. No subscription, no seats, no card to start.
$50Free
credit
to start · no card required
After the credit, top up and keep going. Billed only on the citations that check out, in tiers by how many pass. No clock, nothing expires.
  • Pay only for cites that check out. Priced in tiers by how many pass
  • $10 floor when nothing checks out, so a bad draft costs almost nothing; a passed cite is never billed twice on the same matter
  • Full four-level ruling on every citation: existence, quote, proposition, good law
  • Signed Audit Capsule on every verdict
Start free →

SaaS PII Shields

  • Claude Shield
  • ChatGPT Shield
  • Gemini Shield

Kingsfield is a citation-verification tool, not a law firm. It gives no legal advice and forms no attorney-client relationship. A pass is not a guarantee that a citation is correct or good law; you make the final decision on every result. See the Terms of use and Legal & limitations.

Common questions

Before you verify.

Can I trust AI to check my AI?

Kingsfield rules against real court records, with a different model and a different corpus than the one that drafted your brief. When the corpus cannot confirm a citation, it returns INCONCLUSIVE instead of guessing. Every ruling comes back as a signed Audit Capsule you can open and inspect.

Which courts and states does Kingsfield cover?

Federal law and 19 states are live today: AK, CA, DE, FL, IL, NV, NY, PA, TX, VT, WY, LA, MS, GA, RI, MA, CT, NH, ME. We add new state corpora on a rolling basis and are on track to cover all 50 states within about 90 days. Anything outside the covered corpus is marked not checked, never failed, so you always know exactly what was verified.

What will I pay, and for what?

You pay only for the citations that check out, the ones Kingsfield confirms you can safely file, priced in tiers by how many pass. If a draft is full of fabrications, you pay the $10 floor and nothing more. We bill on confirmations, not rejections, on purpose: a verifier paid per rejection would over-reject, so we only get paid when your cites are good. $50 free to start, no card, no subscription, and it is recoverable from your client as a disbursement.

Why do I have to verify my bar number?

It is a legal safeguard, not a hoop. Citation rulings delivered to an unlicensed user could be construed as the unauthorized practice of law, so we gate access to verified, licensed attorneys. It also keeps you in the judgment seat: Kingsfield checks the cites, you make the call.

Is my client's data safe?

The PII Shield tokenizes client identifiers in your browser before any draft leaves your machine, so the cloud receives a de-identified draft. A fail-closed firewall turns away anything PII-shaped, and the judge keeps only a payload hash and the verdict, never the draft itself. See Trust & security.

Why is the PII Shield free but required?

The Shield is our own egress firewall. We require it because it protects Kingsfield first: it guarantees no client PII ever reaches our server. You do not charge someone for the lock you make them put on your door, so it is free. Protecting your privilege is the second benefit.

Are you SOC 2 or ISO certified?

No, and by design we do not need to be. Those attestations describe how a vendor handles the client data it retains. Because the PII Shield keeps that data on your machine, Kingsfield retains none, so there is nothing for such an audit to examine. We chose real protection by architecture over a certificate. If your risk review needs documentation, we are glad to walk you through exactly how the egress firewall works.

Can you protect my client data in my other AI tools?

Yes, as a paid custom build. The free Shield protects the Kingsfield workflow. Most cloud AI tools give client data no on-device protection: it leaves your machine to be processed. For firms that want privilege protection across their whole AI stack, we build a custom Shield, with the token-to-PII map never leaving their machines.

What about cases outside your corpus?

They are marked not checked, never failed. We state plainly which authority we could verify, so you always see what was and was not checked. Coverage grows weekly.

Does this replace my review or give legal advice?

No. Kingsfield checks citations, not legal merits, and forms no attorney-client relationship. A pass is not a guarantee that a citation is correct or good law. You make the final call on every result and keep your Rule 11 duty. See Legal & limitations.

$50 free to start

Rule your AI draft
before you file.

Run your AI-written brief through the full Kingsfield ruling: every citation checked for existence, every quote checked against the opinion, every proposition checked against the holding. You get back a signed Audit Capsule. Start with $50 in free credit, no card. You pay only for the citations that check out, in tiers by how many pass; a draft full of fakes costs just the $10 floor. No subscription.

How a ruling works
  1. 1

    Create your account, get $50 in credit

    Sign up with your name, work email, and a password, then confirm your email. Your $50 in free credit lands the moment you confirm. No card, no bar number, no waiting. Kingsfield is built for legal professionals; it verifies citations and gives no legal advice.

  2. 2

    Install the PII Shield

    The Shield strips client PII in your browser before any draft leaves your machine, so nothing identifiable ever reaches our server. It is free because we require it: it protects our server first, your privilege second. You set it up from your portal once you're in.

  3. 3

    Submit your draft, get the ruling

    Inside the portal you paste your AI-written brief. The full four-level ruling runs against the live corpus, then returns the verdict and a signed Audit Capsule for the file. You pay only for the citations that check out; a bad draft costs just the $10 floor. Top up to keep going.

  4. 4

    Protect your client PII with other AI tools

    Kingsfield offers the same PII Shield protection across other cloud AI tools as custom builds. Available on request.

696/700 court-confirmed AI citation errors ruled right
Step 1 · Start free · $50 credit

This tool provides citation verification, not legal advice. It is intended for legal professionals. Use of Kingsfield does not create an attorney-client relationship.

Step 2 · Install the PII Shield

The Kingsfield PII Shield comes with your account. It strips client PII in your browser before any draft leaves your machine, so nothing identifiable reaches our server. You set it up from your portal once you confirm your email and sign in.