Russian to English Law/Patents Law: Taxation & Customs RF Customs Code

From art. 358 of the RF Customs Code: "При проведении таможенного контроля таможенные органы исходят из принципа выборочности и, как правило, ограничиваются только теми формами таможенного контроля, которые достаточны для обеспечения соблюдения таможенного законодательства Российской Федерации."

I am editing a document where "принцип выборочности" has been rendered as "selective application" of customs oversight measures. Unfortunately, "selective" doesn't work well as a modifier in AE for any kind of law enforcement effort; it implies that the enforcers sometimes enforce the law; and sometimes not. So...

Multitran gives "optionality" for "выборочность," which doesn't do the trick here, as I believe what is being "selected" by this principle is a part of what is being processed by Customs (i.e., you bring in 3 containers, they check all the paperwork for only one of them, selected at random).

Personally, I am leaning toward "sampling principle" or "principle of spot checks," but I am open to informed suggestions.