The Public Health Act, 1897 is the primary legislation governing public health in India. It provides for the prevention and control of diseases, the promotion of public health, and the regulation of sanitation and hygiene.

The primary responsibility of the Central Government under the Public Health Act, 1897 is to coordinate public health activities among the states. This includes providing technical and financial assistance to the states, conducting research on public health issues, and developing national public health policies.

Conducting research on public health issues is not a function of the State Government under the Public Health Act, 1897. This is the responsibility of the Central Government.

The purpose of the Epidemic Diseases Act, 1897 is to prevent and control the spread of epidemic diseases. It empowers the government to take special measures to prevent the spread of diseases, such as quarantining infected persons, closing schools and public places, and regulating the movement of people and goods.

Providing healthcare services to the population is not a power of the government under the Epidemic Diseases Act, 1897. This is the responsibility of the Ministry of Health and Family Welfare.

The National Health Policy, 2017 is a statement of the government's vision for the health sector. It outlines the government's goals for improving the health of the population, and provides a framework for the implementation of public health programs.

The key objectives of the National Health Policy, 2017 are to improve the health of the population, reduce the burden of disease, promote healthy lifestyles, and ensure access to affordable healthcare services.

Increasing the budget for healthcare is not a key strategy for achieving the objectives of the National Health Policy, 2017. The key strategies are strengthening the public health system, promoting healthy lifestyles, and expanding access to healthcare services.

The Mental Healthcare Act, 2017 is a legal framework for the regulation of mental healthcare services. It provides for the rights of persons with mental illness, the establishment of mental health institutions, and the regulation of the practice of mental healthcare professionals.

The key provisions of the Mental Healthcare Act, 2017 include the right to free and quality mental healthcare services, the right to informed consent for mental healthcare treatment, and the right to refuse mental healthcare treatment.

Lack of political will is not a key challenge in the implementation of public health law in India. The key challenges are lack of resources, lack of public awareness, and lack of trained personnel.

To improve the implementation of public health law in India, it is necessary to increase funding for public health programs, raise public awareness about public health issues, and train more public health professionals.

The judiciary plays a crucial role in the implementation of public health law by interpreting public health laws, enforcing public health laws, and reviewing the constitutionality of public health laws.

All of the given cases are landmark cases in the field of public health law in India.

The Jacob Mathew v. State of Punjab case established the right to clean drinking water as a fundamental right under Article 21 of the Constitution of India.