LexFlip: A Dissociation Diagnostic for Legal Meaning Preservation Metrics
LexFlip releases 373 minimal perturbations of Quebec statutory French that reverse legal force while preserving tokens, exposing weaknesses in embedding-based meaning preservation metrics.
LexFlip provides 373 minimal perturbations of Quebec statutory French that reverse legal force while preserving 0.93 of tokens, creating dissociation items that break monotone token-overlap metric validation. The seven embedding and BERTScore metrics tested register only 0.022-0.039 of their identical-to-unrelated range on these edits, versus 0.670 for bidirectional NLI. Against FrJudge, with a measured human ceiling of r=0.597, a bare length feature outscores every semantic metric tested.
- Dissociation design holds surface form fixed while legal force moves, disqualifying overlap-based validation.
- Bidirectional NLI spends 0.670 of the metric range versus 0.022-0.039 for embedding metrics.
- On FrJudge a bare length feature outscores every tested semantic metric.
From the original article
1 min read at arxiv.orgDoes a simplified legal clause still say what the original said? The checks in current use cannot establish that it does: requiring an identical pair to score highest and an unrelated pair lowest moves lexical overlap and legal force together, so any monotone function of token overlap satisfies both. Our remedy is a dissociation, an item holding surface form fixed while legal force moves.
By Gaurab Baral · arxiv.org
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