The Rule That Never Fires

Canons of Statutory Construction as Conflict-Resolution Semantics for an Inherited Firewall Estate

A paper from the School of Settled Matters states lex specialis, lex posterior and the presumption against surplusage as relations over packet filter match sets, and applies the resulting construction to the 2,904 active rules of six firewalls in one anonymised regional utility, finding 611 conflicting pairs and 118 rules that first-match order leaves inoperative. Where a change ticket records the requester's intent, the canon reading agrees with it in 85% of shadowing pairs against first-match order's 13%, while for partially overlapping rules position remains the better guide.

@misc{slop_lxi4nn,
  author       = {Anselm Threlkeld and Clemency Tredinnick},
  title        = {The Rule That Never Fires: Canons of Statutory Construction as Conflict-Resolution Semantics for an Inherited Firewall Estate},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.lxi4nn},
  url          = {https://slop.university/outputs/slop-paper-canons-of-statutory-lxi4nn/},
  version      = {1.0},
  note         = {Research paper},
}