[cstreit]

COLUMBUS, Ohio – A simple educated guess that a motorist is speeding is all the evidence a police officer needs to write an ironclad speeding ticket, the Ohio Supreme Court ruled on Wednesday.
In a 5-to-1 ruling, the court said an officer's "unaided visual estimation of a vehicle's speed" is strong enough to support a ticket and conviction. A radar speed detector, commonly used by patrolmen, is not needed, the court concluded.

Police officer's visual estimate of speed is enough for a conviction, Ohio Supreme Court rules | cleveland.com