Madhu sir, you know well, Unions will sure to object introduction of bio-metric attendance marking for obvious reasons. Especially it will create problems for union functionaries who move around freely without work or even they won't step into the punching gates, that you know very well. Instances have been noted, some even go out and concentrate on their side businesses, money lending etc, also heard some even work elsewhere by marking present here misusing their positions in union. These employees who sees many inconveniences won't tolerate, tampering the machine itself as these became the cause curtailing their free movement during working hours. When I was with a mining co. some time in 90's we tried to introduce bio-metric using our internal telephone lines but due to non-cooperation of workers/union this project was drop after trial run.