Status of leave encashment under statute

Please any one can help me in status of leave encashment in case of statute. If the Company accumulates the leaves and if the person is unable to take any leave due to work or any rejection of leave application is the simultaneously the leave lapse above the accumulation criterea. What is the legal stand, is there any notification to support and bring in the fairness in practise. Please help in this context.

Thanks & Regards

Amal Shere