The most common and most likely answer to this crossword clue is the 10 letter word LEGALISTIC
I've seen this crossword clue in Independent
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More clues leading to the result LEGALISTIC
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The straight part
We know that "according to law" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case according to law = legalistic.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does LEGALISTIC mean?
LEGALISTIC adjective- Of a person, following the letter of the law.
- Of a person, tending to resort to the law, as one who sues frequently.
- Practicing or characterized by legalism.