The document calls bonds illegal as they are against Article 19 of the Indian Constitution (Right to work; which also implies a right not to work)
But, by the same argument, aren't notice periods also illegal?
Also, if a workman returns after long absenteeism period (say 1 year), will we go against the above principle if we ask the employee to submit a medical fitness certificate before we take him back and deploy him on the job. Alternatively, can we ask for a written declaration from him on where he was engaged during the period of his absence (just to confirm that he was not involved in any illegal activities; that he was not admitted in any mental institution, etc.)