Peter Barnett made hundreds of journeys from his home in Oxford to London's Marylebone station without buying tickets.
The 44-year-old was caught when he was stopped by a ticket inspector at Marylebone, claiming to have travelled from Wembley instead of Haddenham & Thame Parkway in Oxford.
City of London Magistrates' Court heard that Barnett had received a conditional caution in 2010 for a similar offence.
But the father-of-three dodged a trip to jail today when a judge gave him a prison sentence of 16 weeks, suspended for 12 months.
Deputy District Judge Olalekan Omotosho told him his serial fare-skipping was a "serious offence", saying: "There is a need not just to punish you for the offences but also deter others from committing offences."
She added: "It is a shame, really, because you had it all. It remains unclear why you acted so badly. You let yourself down and your family down, particularly in light of your profession as a lawyer."
The court was told that Barnett - a former Oxford graduate and Rhodes scholar who also worked in the financial services sector - failed to pay for journeys on Chiltern Railways on 655 days between April 2012 and November 2014.
Prosecutors argued that he should pay back £19,689, the full value of the cost of daily returns for the trips he made.
Richard Doolan told the court: "The obligations of a person using the train must be to have a valid ticket for the whole of their journey, any time they want to travel."
But Angus Bunyan, defending, claimed that value equated to the penalty imposed by the railway company, rather than a true value that the criminal court should consider.
And he said it was "common sense" that Barnett would not have paid for daily trips he dodged, but rather for a weekly ticket, so should not pay back based on a daily amount.
He said: "No commuter, if they were going from Haddenham & Thame to London, would buy a full single, then have his day in London, and buy another full single back."
Mr Bunyan argued that Barnett should pay back £5,892.70, which he said was the actual cost of the trips he had taken.
He said: "The point is, he did buy weekly tickets, despite how short the journey - they were just the wrong ones.
"His behaviour, unlawful as it was, demonstrates that he did buy weekly tickets.
"Our submission is that Chiltern Railways' policy isn't relevant to the decision the court has to take, otherwise we would be substituting a private company's statutory regime for the sentencing guidelines."