"Mr. Engler did not endanger the safety of another person, nor was there a public disturbance,” prosecutors said, according to CBS.
Prosecutors also say the pat-down was "likely improper," strengthening Engler's defense and making a conviction "highly unlikely."
"A legal argument could be made that Mr. Engler’s actions, considered to be resisting, were a reaction to an unlawful search," prosecutors said, according to CBS. "This makes proving the State’s case beyond a reasonable doubt highly unlikely.”
The Engler episode was just one in a string of embarrassments for the Secret Service last year. In April, a number of agents were implicated in a drinking and prostitution scandal in Colombia as they prepared security for a visit by Obama. The incident caused an uproar on Capitol Hill, where Republicans launched an investigation into whether Obama's security was ever breached. A number of agents resigned in the wake of the scandal.