Government statistics released yesterday show there were just 36 rape and attempted rape convictions during 2010/11, compared with 54 in the previous 12 months.
The number of cases being brought to court by prosecutors also fell by 31% from 118 to 81.
The Crown Office and Procurator Fiscal Service (COPFS) said the drop was a result of the Supreme Court Cadder ruling, which prevents police officers interviewing suspects without access to a solicitor.
Alan Pollock, of Stirling, was filmed intervening in a dispute between an elderly conductor and 19-year-old Sam Main aboard a ScotRail Edinburgh-Perth train on Friday.
During the video (which is shown above, via YouTube) Mr Pollock, a performance manager at finance firm BlackRock in Edinburgh, received a round of applause from fellow passengers after forcibly removing Mr Main from the train.