Roman Republic Æ semis(8.20g, 22.3mm), L.P.D.A.P. series, circa 91 B.C.. Rome mint. Laureate head of Saturn right; behind, S / Prow right; above, L.P.D.A.P.. Crawford 338/2
Ex RBW Collection, privately purchased from Veres/Devine, 12/8/1991
Circa 91 B.C. the Roman Senate passed the Lex Papiria de Assis Pondere, "The Papirian law on the weight of the as", often referred to as the Lex Papiria. The Lex Papiria reduced the weight of the bronze coinage to the semuncial standard, half the weight of the existing uncial standard, and also reauthorized the minting of the silver sestertius, of which there are a complementary series with the letters "E.L.P." also referring to the Lex Papiria.
Given the relatively tiny amount of bronze minted during this period compared to the massive silver issues the law seemingly had little real effect and find evidence suggests these bronzes were largely rejected by the citizens who preferred the earlier, heavier bronzes. Less than a decade later, perhaps because of how unpopular the new bronze weight standard was, the Republic ceased minting of bronzes entirely but the semuncial standard was eventually revived during the coinage reforms of Augustus who struck asses at a roughly semuncial weight standard of 11-13g.