How come prem's gawahi matter

i do not understand, if someone's gawahi other than mukti could put sharad in jail, why didnt prerna's gawahi do it. she also could have said that sharad confessed his crime in front of her...

these people dont know the rules of court...if no one trusted prerna, is it that the court will also not trust prerna...n now that everyone know abt it, court will accept what prem says....

did they forget the long famous dialogue of hindi movies: adalat saboot mangti hia...i dont agree that they shd put sharad in jail without seeing those cassettes that sneha saw in speed.com