Full Idea
The way to get maximum advantage to yourself from justice is to treat the laws as important when other people are present, but when there is nobody else with you to value the demands of nature.
Clarification
'Law' is the Greek word 'nomos', which also translates as 'convention'
Gist of Idea
To gain the greatest advantage only treat law as important when other people are present
Source
Antiphon (fragments/reports [c.439 BCE], B44A), quoted by Anon (Oxy) - Oxyrhynchus Papyrus 1364A
Book Reference
'The First Philosophers', ed/tr. Waterfield,Robin [OUP 2000], p.265
A Reaction
This looks like a pretty good description of the majority of people active in politics.