Being a principal employer we are responsible then what about contractor? why we are paying them?

Respected All, Kindly advise about contractor responsibilities in disputed cases (court matter).
Being a principal employer we are responsible then what about contractor? why we are paying them?
Pl. need you guidance and advise

What are the cases you are talking about? What are the charges you are paying? For what reason?

One of our employee(argon welder) who is on contractor roll has file case in labour court for less increment in compare to his colleague who is more efficient than complainant. Contractor has generate bill for legal expenditure (including lawyer fees). we are paying service charges (as per agreement )in every month to the contractor while they are generating salary bill.
So, who is responsible to pay legal expenditure to the lawyer.

If contract workman not directly Controlled by Principal Employer only in that case you can keep yourself away from such litigation else you need to defend such cases with all your resources including Financial.