Two cases, side by side. Pulled in parallel: file numbers, applicants, DOIs, body parts, employers, carriers, attorneys, tasks, next events. Then the overlap analysis — same applicant? same employer? overlapping body parts (LC 4664 credit territory)? overlapping TD periods (Acme Construction credit territory)? The skill an attorney runs when a new case lands with the suspicion that something on file already touches it.
At the prompt:
aaicase> compare Doe and Roe
aaicase> compare [CASE-ID-A] and [CASE-ID-B]
aaicase> side by side: case 142 and case 287About thirty seconds later you get a two-column comparison table covering 13 fields, followed by an overlap analysis section that flags the legal-credit traps. The skill is short on purpose — it’s a diagnostic to decide whether deeper work (health check, audit, attorney settlement analysis) is warranted on one or both cases.
If either argument is a name, the skill resolves it via merus-search first — with the same disambiguation rules as everywhere else in AAI (list matches, ask the attorney to pick if ambiguous). Then four parallel fetches:
/caseFiles/view/[CASE-A] → case A header + applicant
/caseFiles/view/[CASE-B] → case B header + applicant
/injuries/view/[CASE-A] → case A DOI + body parts
/injuries/view/[CASE-B] → case B DOI + body partsRequired: both case views — comparison is meaningless without them. Optional: the two injury views — if either fails, the DOI/body-parts row is blank for that side and the skill notes the limitation. Everything lands in a per-run mktemp -d directory locked to chmod 700, deleted at the end.
| Field | Case A | Case B |
|---|---|---|
| File # | [#] | [#] |
| Status | Open / Settled / Closed / Archived | same set |
| DOI | YYYY-MM-DD | YYYY-MM-DD |
| Type | SI / CT | SI / CT |
| Body Parts | list from injury record | list from injury record |
| Employer | from party records | from party records |
| Carrier | from party records | from party records |
| Claim # | carrier claim number | carrier claim number |
| ADJ # | EAMS case number | EAMS case number |
| Venue | WCAB office | WCAB office |
| Attorney | attorney of record | attorney of record |
| Open tasks | count (after noise filter) | count |
| Next event | date + type | date + type |
The table is intentionally compact. It’s a glance-and-go format — the attorney scans the rows, spots whatever’s different (or the same), and decides what to do next.
Below the table, the skill flags four kinds of overlap:
| Check | Trigger | What it tells you |
|---|---|---|
| Same applicant? | Both cases have the same applicant contact | Multi-case client — LC 4664 territory if body parts overlap |
| Same employer? | Same employer party on both | Could be same-employer-different-DOI (e.g. cumulative + specific) or co-employee scenarios (Rule 1.7) |
| Overlapping body parts? | Body parts in case A intersect with case B | Direct LC 4664 credit analysis — the prior case’s award reduces the current case’s PD recovery on the shared body part |
| Overlapping TD periods? | TD activity dates in case A overlap with case B | Acme Construction credit — you can’t collect TD from two carriers for the same week |
The flags are presented as observations, not conclusions. The skill says “LC 4664 credit analysis may apply” — whether the credit actually applies depends on whether a prior award exists (an Award or signed Findings & Award document), not just whether body parts overlap. The attorney does that determination.
Example: a client had a 2018 case with a 10% PD award to the lumbar spine. The current case is 2024 with a QME finding 20% PD to the lumbar spine. LC 4664 means the client only recovers 10% PD on the current case — the prior 10% comes off.
The skill flags this when body parts intersect:
Overlapping body parts: lumbar spine. LC 4664 credit analysis may apply — check Case A for a prior PD award to the lumbar spine; if one exists, the prior PD% reduces this case’s PD recovery.
What the skill doesn’t do (and shouldn’t):
What it does do is flag the question so the attorney doesn’t go to a settlement conference unaware that the prior case exists.
Acme Construction Sons v. WCAB (2006) holds that an applicant cannot collect TD from two carriers for the same week. If Case A and Case B both have TD payment activity during the same period, one carrier is entitled to credit for what the other paid.
This commonly comes up when:
The skill flags overlap based on TD activity dates in each case. The actual credit determination depends on which carrier paid first, what kind of credit (offset vs. reimbursement), and what the carriers’ respective payment logs show — not the kind of analysis a case-file comparison can do alone. But the flag is enough to make sure the attorney knows to dig.
Same applicant + different DOIs is the most common multi-case pattern at this practice. Workers with long employment histories accumulate cases over the years. The skill flags it explicitly:
Same applicant: Jane Doe. This applicant has both cases at the firm. Coordinate strategy — consolidated settlement may be possible (LC 5275 stipulation), and any prior PD awards on Case A reduce current PD recovery on Case B (LC 4664) for shared body parts.
The follow-up workflow:
Different applicants but the same employer raises Rule 1.7 conflict questions, especially when the cases involve co-employees as witnesses or when the firm’s overall posture against the employer affects either matter. The skill surfaces the overlap; the attorney determines whether a conflict actually exists.
This is the same Rule 1.7 check new case performs during intake. Compare-cases catches it later — for example, when an existing case is being compared against a candidate intake, or when an attorney is auditing the firm’s posture against a frequent-defense employer.
CASE COMPARISON
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
| Field | Case A: Doe v. Sample Co. | Case B: Doe v. Sample Co. |
|----------------|------------------------------|------------------------------|
| File # | [FILE-A] | [FILE-B] |
| Status | Settled | Open |
| DOI | 2018-03-12 | 2024-09-08 |
| Type | SI | CT |
| Body Parts | lumbar spine, right knee | lumbar spine, cervical spine |
| Employer | Sample County Agency | Sample County Agency |
| Carrier | Sample Insurance Co. | Sample Insurance Co. |
| Claim # | [CLAIM-A] | [CLAIM-B] |
| ADJ # | [ADJ-A] | [ADJ-B] |
| Venue | Anaheim WCAB | Anaheim WCAB |
| Attorney | Sample Attorney | Sample Attorney |
| Open tasks | 0 | 4 |
| Next event | — | 2026-06-04 MSC |
OVERLAP ANALYSIS:
✓ Same applicant: Jane Doe — yes, multi-case client
✓ Same employer: Sample County Agency — yes
✓ Body part overlap: lumbar spine — LC 4664 credit territory
Body part unique to A: right knee
Body parts unique to B: cervical spine
⚠ TD periods: not yet analyzed (run audit on each case to surface payment-history activities)
FLAGS:
⚠ LC 4664: Case A is settled with PD award (status: Settled). If the
A award included PD to the lumbar spine, the current Case B PD
recovery on the lumbar spine is reduced by that amount. Pull the
Case A Award document — run "audit on [CASE-A]" to surface it.
⚠ Same employer + same applicant + different DOIs: consider whether
Case B (CT) should be amended to include the period after A's DOI
if exposure continued. LC 5500.5 election may apply.
NEXT STEPS:
1. Run "audit on [CASE-A]" to find the Award document and prior PD%
2. Run "audit on [CASE-B]" to surface the current TD/PD payment history
and any unaddressed body parts in the Application
3. Attorney applies the LC 4664 credit to the current case's PD analysis
once the prior PD% is in hand (rate computation is attorney work)Merus stores body parts as free-text strings (“lumbar spine”, “low back”, “L5-S1”) which the skill normalizes for the overlap check. If the normalization treated “lumbar spine” and “cervical spine” as the same (it shouldn’t), file a bug. If you’re seeing “low back” treated as different from “lumbar spine,” the body-part terminology mapping may need expansion.
The skill notes which side has the gap. If body parts are blank for Case A, the body-part overlap row reads “Case A body parts unknown.” Fill in the injury record in Merus and re-run.
The skill will show identical rows across most fields. That’s informative — it confirms the duplicate. Decide which case is the canonical one; consider running audit case on both to see which has the uploads, then handle the duplicate through the Merus UI (the skill won’t delete a case).
The skill is intentionally pairwise. Run multiple comparisons (A vs. B, A vs. C, B vs. C) and read the three outputs together. The pairwise format keeps each comparison focused.
Merus stores the employer as a contact/party. If two subsidiaries are entered as separate contacts, the skill correctly treats them as different employers. If they’re entered as the same parent company across both cases, the skill flags as same. The right granularity depends on the firm’s contact discipline.
Part of AAI for MerusCase — code-guarded AI case intelligence for California Workers’ Comp attorneys.