From:
sixthformlaw.info/03_dictionary/dict_d.htm

de minimis

[Latin: insignificant; minute, frivolous]
Something or some act which is 'de minimis' is one which does not rise to a level of sufficient importance to be dealt with judicially.

In Canadine v Director of Public Prosecutions [2007] QBD, it was held that a speed camera complied with the relevant regulations (Traffic Signs Regulations and General Directions 2002) where a minor irregularity in the casing around the sign (which was not an integral part of the sign) could only be seen on very close inspection and no motorist would have been misled as to the true nature of the sign, accordingly even if the casing had been part of the sign the transgression from the regulations would be regarded as de minimis.