In recent years, the practice of contractualization or endo has been a hotly debated issue in the Philippines. The scheme involves hiring workers on a contractual basis, usually for a fixed period of time or project, without the guarantee of regular employment. While some argue that it offers flexibility to businesses and helps create jobs, many labor groups and experts consider it illegal and detrimental to workers` rights and job security.

First and foremost, contractualization violates the principle of security of tenure, which is enshrined in the Philippine Labor Code. This means that employees have the right to job security and cannot be terminated without just cause and due process. However, with contractualization, workers are subjected to unstable employment arrangements that can end without warning or explanation. They are also denied benefits and protections that regular employees are entitled to such as leave credits, separation pay, and healthcare insurance.

Furthermore, contractualization has become a tool for companies to evade regular employment and deprive workers of their basic rights and privileges. In many cases, these workers are paid lower wages than their counterparts and have no job security. This allows companies to avoid their responsibilities as employers and shift the burden of providing benefits and social security onto the state.

In addition to this, contractualization also undermines the workers` right to unionize and collective bargaining. Since the workers are employed on a contractual basis and may not have the same benefits and protections as regular employees, they are often less likely to form or join unions. This can leave them vulnerable to exploitation and abuse, as they have less bargaining power and are unable to negotiate for better wages and working conditions.

Finally, contractualization can have negative effects on the economy as a whole. When workers are unable to secure stable employment, they often have less disposable income and are less able to contribute to the economy through consumer spending. This can then negatively impact businesses and lead to lower economic growth.

In conclusion, contractualization is considered illegal for various reasons, including its violation of the principle of security of tenure, its detrimental effects on workers` rights and job security, its ability to evade employers` responsibilities, and its potential negative impact on the economy. As such, it is important for companies and policymakers to recognize these issues and work towards ensuring that workers` rights are protected and that they can enjoy stable and secure employment.