Specialist/expert Witnesses

[Joanne]

Roy Meadows, an expert witness (well not really) managed to get at least 3 ladies jailed on 'cot death/murder charges', Angela Canning, Trupti Patel and Sally Clarke, he came up with elaborate statistics which convinced the juries to find these people guilty, in the end the statistics didn't add up and the ladies were released. Unfortunatly, Sally Clarke died due to alcholism and the marriage of Angela Cannings broke down.
So, should these experts be allowed in a court room? Can their evidence be used to jail people? What do other people think?