MOSCOW, Idaho — Officials say a highway district’s attempt to slow drivers on some Latah County roads is unenforceable in court. The North Latah County Highway District has posted 35 mile per hour signs on most of its county roads. But district secretary Dan Carscallen says the legal limit is actually much faster — 55 miles per hour. Carscallen says state law prohibits highway districts from setting hard speed limits unless expensive traffic surveys are conducted on each road. That means that many of the signs in Latah County are advisory, the Lewiston Tribune reports. Latah County sheriff’s Chief Deputy Brian Strampher says 35 miles per hour is probably the prudent speed for the roads. But when deputies have tried to enforce the lower limit with tickets, they’ve lost in court.