https://www.theguardian.com/uk-news/2018/aug/14/guernsey-resident-halts-road-works-with-ancient-plea
Rosie Henderson, from Guernsey, raised the clameur by kneeling and calling for help and reciting the Lord's Prayer in Norman French. Fully enforceable in Guernsey and Jersey law, it means the construction work in St Peter Port must stop until a court decides the case.
Giles would have loved it.
It does seem to be used comparatively often,
I think it's a nice idea