Pre-Motion — adversarial premortem for UK litigation

You think you've built the strongest version of your case. Pre-Motion runs it through a structured adversarial pipeline to find where it actually loses — the procedural, substantive, evidentiary, and strategic failure modes opposing counsel will pull on first. The opposite of confirmation bias, by design.

For: solicitors stress-testing before issue, in-house counsel before sign-off, mediators valuing settlement, litigation funders pricing a matter, anyone deciding whether to take a case.

How it runs

Four passes over the matter. Run the four adversarial passes in Stage 3 as parallel sub-agents if your environment supports them; otherwise run them in sequence — the method and the output are the same either way.

1. Optimistic baseline. Build the strongest version of the case the evidence supports. This is the foil for everything that follows.
2. Evidence inspection. Three checks: document review (gaps, weak documents), cross-reference (one document contradicting another), chronology (timeline gaps, dates that don't fit). Produce evidence flags with a severity each.
3. Premortem adversary. Four adversarial passes, one per failure category below. Give each the same frame: "It is [trial date + 1 year]. This case has been LOST. Walk back — what in your category caused the loss?" Produce ranked failure scenarios per category.
4. Synthesis. Diff the optimistic baseline against the adversarial findings. Produce the brief.

--depth=fast runs a single combined adversarial pass for a quick read; --depth=thorough runs all four passes in full.

Inputs

• Matter facts: parties, brief chronology, claim heads, jurisdiction, forum.
• Evidence references: documents, witness statements, expert reports — pointers to matter content, not re-uploaded.
• The strongest version of the case as the user sees it (the optimistic baseline).
• Optional: the counterparty's pleaded or anticipated defence.
• Optional: --depth=fast|thorough.

Step 1 — Permitted-use check (CPR 31.22 + privilege)

Before reading matter documents:

• The host workspace enforces the hard gate (matter-slug match against the proceedings reference, privilege posture). If this skill is running, that gate has already passed — this step does not replace it.
• Still confirm with the user: are any documents drawn from disclosure in other proceedings? If so, stop until permission, the parties' agreement, or open-court reference is established (CPR 31.22 implied undertaking).
• If the matter's privilege posture is mixed, add a [PRIVILEGE FLAGGED] banner to the output and recommend counsel review before any external distribution.

Failure-mode categories

The four Stage 3 passes specialise in the four ways UK civil cases lose.

Procedural

• Limitation expired or contested (Limitation Act 1980, s.5 / s.11 / s.14A).
• Pre-action protocol non-compliance (Pre-Action Conduct PD, sector protocols).
• Strike-out or summary-judgment vulnerability (CPR 3.4, CPR 24).
• Costs sanctions risk (CPR 44.2).
• ADR refusal exposure (Halsey; Churchill v Merthyr Tydfil [2023]).
• Service / jurisdiction defects (CPR 6).
• Disclosure-regime missteps (CPR 31 vs PD 57AD).

Substantive

• Cause-of-action elements unproven.
• Causation gaps, factual or legal (Wagon Mound, Fairchild, SAAMCO).
• Mitigation failures (British Westinghouse).
• Affirmative defences (estoppel, waiver, release, contributory negligence, ex turpi causa).
• Statutory bars (Consumer Rights Act, UCTA, statutory limitation).

Evidentiary

• Privilege exposure (Unilever exceptions, joint-defence breakdown, Rush & Tompkins boundary).
• Disclosure failures and adverse-inference risk (CPR 31, PD 57AD).
• Witness credibility, availability, inconsistency.
• Hearsay weaknesses (Civil Evidence Act 1995 s.2–4 notice failures).
• Expert-report deficiencies (CPR 35; joint-instruction failures; Toth v Jarman).
• Document authenticity and chain of custody.

Strategic

• Settlement leverage misjudged (BATNA gap to the opposing side).
• Cost/benefit ratio misaligned with client objectives.
• Reputational or regulatory exposure from issue or trial.
• Information asymmetry working against the client.
• Counterparty's BATNA stronger than the optimistic baseline assumes.

Each pass should cite the relevant authority for its category, and mark any rule or case it cannot pin to a section or citation with [CITE NEEDED] rather than stating it as settled.

Output

Produce the brief with the sections below. Render it as the finished brief — do not echo this list back as a template, and do not invent facts to fill a section; if a section has nothing in it, say so.

• A reviewer-note line: work product, prepared in contemplation of litigation, subject to litigation privilege.
• A header: matter name, date generated, depth, privilege posture, and the verdict (Steelman / Borderline / Strawman).
• The one brutal sentence — "If we lose this, this will be why: [single sentence]."
• Optimistic baseline — the strongest version of the case, as the baseline pass built it.
• Ranked failure scenarios — grouped Procedural / Substantive / Evidentiary / Strategic. Each scenario is one paragraph with a Severity (H/M/L), a Likelihood (H/M/L), and a Mitigation.
• Evidence inconsistencies — the flags from Stage 2.
• Blind spots — issues the baseline assumed resolved that the adversary found open.
• Mitigations — one concrete action per scenario where applicable: strengthen evidence, amend pleadings, settle, withdraw, brief counsel differently.
• Settlement-posture implications — qualitative only. Translate the failure profile into posture, e.g. "several procedural failure modes ranked H — settle harder than the baseline suggests; consider a Calderbank offer before issue." Produce no number; full BATNA / ZOPA analysis belongs to the v0.2 settlement-helper skill.

Mark uncertainty inline as you go:

• [SME VERIFY — failure mode] — borderline adversary output; counsel's call.
• [CITE NEEDED — authority] — a rule or doctrine referenced without a section or case; verify before relying on it.
• [EVIDENCE FLAG — severity] — surfaced by Stage 2; check against the source document.

What this skill does not do

• Predict the outcome. It surfaces failure modes; outcomes depend on the tribunal, the judge, the witnesses, the day.
• Take the case for you. The verdict (steelman / strawman) is the model's read of the brief, not advice.
• Replace counsel's strategic call. Settle, withdraw, strengthen — all counsel decisions.
• Cover non-UK procedure (US federal, Scotland, NI).
• Run during trial. This is pre-action, pre-settlement, or pre-funding use.
• Replace a formal counsel opinion. A KC's view on case strength matters more than this output. Pre-Motion is a structured prompt for that conversation, not a substitute for it.

v0.2 roadmap

A separate settlement-helper skill covering Calderbank / Part 36 mechanics and BATNA / ZOPA / Nash bargaining — the quantitative settlement analysis deliberately kept out of this skill.