Michael Ruse's attorney says his client "needs help with regards to thinking skills." There's a good reason why.

The 21-year-old British man on trial for assault was convicted this week after he celebrated getting away with the crime by posting to Facebook, the Telegraph reported.

Ruse, of Leigh Park, was on trial for attacking his friend's father with a baseball bat and a baton. Reports say Ruse thought he was nearly off the hook when he shared the confession on the social network.

"Yeah I think I get [sic] away with it tbh [to be honest] x," he wrote, according to the Daily Mail.

Six people "liked" the update, but one so-called friend saw the statement and printed out the text as evidence for prosecutors, in effect forcing Ruse to change his plea from not guilty to guilty.

Judge Ian Pearson was unsympathetic to Ruse's reckless status update.

"You pleaded guilty part way through the trial only really because you were stupid enough to put on Facebook what amounted to a full confession," Pearson said.

Ruse was sentenced to 46 weeks in prison.