Definition

Source freshness tracking is the practice of storing and using “currency” metadata for each document in an index: last updated time, publication date, effective (in-force) dates, and version identifiers. It helps a retrieval system prefer the most current applicable sources and flag potentially outdated material.

Why it matters

Legal change is constant: tax and regulatory rules evolve through amendments and guidance.
Fewer outdated citations: reduces answers that cite superseded versions.
Better ranking: freshness can be a useful tie-breaker among similarly relevant sources.
Operational monitoring: enables alerts for sources that have not been refreshed.

How it works

Freshness tracking is usually implemented as metadata + scoring rules:

Ingest -> extract dates/versions -> store freshness fields -> rank with freshness -> alert on staleness

Common fields:

published_at, updated_at
effective_from, effective_to (or repeal date)
version_id / consolidation identifiers
last_checked_at (when the crawler verified the source)

Practical example

If a consolidated legal article was updated last month, the system boosts it above an older PDF excerpt. If a source has not been checked for a long time, it is flagged for review or down-weighted.

Common questions

Q: Is freshness always good for ranking?

A: Not always. Freshness matters only when the newer source is applicable. Authority and applicability still come first.

Q: How do you prevent “new but irrelevant” boosting?

A: Use freshness as a secondary signal and require strong relevance + applicability filters.

Regulatory Drift Detection - detect changes that require updates
Search Analytics - monitor staleness and failures
Indexing Strategy - ingestion and refresh cadence design
Content Discoverability - make versions and dates searchable
Authority Ranking Model - combine authority with freshness signals

References

Manning, Raghavan & Schütze (2008), Introduction to Information Retrieval.