Get Co Cited

Get authorities most frequently cited alongside this one.

Finds cases that cite this authority, then counts what else those cases cite. Useful for: "what other authorities are commonly referenced alongside s.20 LTA 1985?"

a.id breaks ties in the ordering. Co-citation counts collide heavily in the tail — hundreds of authorities share a count of 1 — so without it two pages of the same query would overlap and skip rows, which is exactly the kind of silent duplication a paging consumer cannot detect.