The delta block and last_checked

The last_checked parameter is DocketLayer’s change detection mechanism. Supply it on any query and the response includes a delta block containing every new filing since that timestamp. Without it, the response contains case context only — no delta block is returned.

How it works

GET /v2/case?case_id=1:24-cv-01234&court_code=nysd&last_checked=2026-01-01T00:00:00Z

If filings have occurred since that timestamp:

{
  "meta": {
    "queried_at": "2026-04-29T12:00:00Z",
    ...
  },
  "delta": {
    "changed": true,
    "since": "2026-01-01T00:00:00Z",
    "change_count": 2,
    "new_filings": [
      {
        "entry_number": 41,
        "filed_at": "2026-03-15T10:22:00Z",
        "filing_type": "motion",
        "filed_by": "Acme Corp.",
        "description": "Motion for summary judgment",
        "document_identifier": "0041",
        "document_identifier_type": "pacer_doc_id",
        "external_url": "https://ecf.nysd.uscourts.gov/doc1/..."
      },
      {
        "entry_number": 42,
        "filed_at": "2026-04-11T14:23:00Z",
        "filing_type": "order",
        "filed_by": "Hon. Sarah Johnson",
        "description": "Order granting motion to dismiss",
        "document_identifier": "0042",
        "document_identifier_type": "pacer_doc_id",
        "external_url": "https://ecf.nysd.uscourts.gov/doc1/..."
      }
    ]
  }
}

If nothing has changed:

{
  "delta": {
    "changed": false,
    "since": "2026-01-01T00:00:00Z",
    "change_count": 0,
    "new_filings": []
  }
}

Managing last_checked correctly

Always use meta.queried_at as your next last_checked. Do not use the current system time or the timestamp of the latest filing.

result = client.get("https://api.docketlayer.ai/v2/case", params={
    "case_id": "1:24-cv-01234",
    "court_code": "nysd",
    "last_checked": last_checked
}).json()

# Store the server's timestamp, not your own
last_checked = result["meta"]["queried_at"]

Using meta.queried_at ensures:

No gap between queries — you never miss a filing that occurred while your code was running
No clock skew — the server’s timestamp is authoritative
Correct timezone handling — queried_at is always ISO-8601 with a timezone offset

Timestamp format

last_checked must be an ISO-8601 timestamp with a timezone offset. A bare date or a timestamp without offset is rejected with 400.

2026-01-01T00:00:00Z          ✓ UTC
2026-01-01T00:00:00-07:00     ✓ with offset
2026-01-01                    ✗ rejected
2026-01-01T00:00:00           ✗ rejected (no offset)

A last_checked value in the future is also rejected with 400.

Filing type filtering

Use filing_types to narrow the delta to specific event categories:

GET /v2/case?...&last_checked=...&filing_types=order,judgment

Only order and judgment entries appear in new_filings. Other filings are not returned in the delta, but the case context is always returned in full regardless of the filter. Common filing type values: complaint, motion, order, judgment, notice, stipulation, hearing, brief, subpoena, settlement.

First query — no last_checked

On your first query for a case, omit last_checked. You receive the case context with no delta block. Store meta.queried_at and use it as last_checked on every subsequent query.

# First query — no last_checked
result = client.get("https://api.docketlayer.ai/v2/case", params={
    "case_id": "1:24-cv-01234",
    "court_code": "nysd"
}).json()

# From here on, always pass last_checked
last_checked = result["meta"]["queried_at"]

delta vs. docket_history

delta.new_filings and case.docket_history (in context=full) are different things:

	`delta.new_filings`	`case.docket_history`
What it contains	Filings since `last_checked`	All filings on record
When present	Only when `last_checked` is supplied	Only when `context=full`
Filtered by `filing_types`?	Yes	No

For a monitoring loop, the delta is what you need. docket_history is for initial intake or full review.

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The delta block and last_checked

How it works

Managing last_checked correctly

Timestamp format

Filing type filtering

First query — no last_checked

delta vs. docket_history

​How it works

​Managing last_checked correctly

​Timestamp format

​Filing type filtering

​First query — no last_checked

​delta vs. docket_history

How it works

Managing last_checked correctly

Timestamp format

Filing type filtering

First query — no last_checked

delta vs. docket_history