Indian landscape
On the basis of Articles 13, 32, 226, 141 and 142 in the Indian Constitution, the full potential of expansion of judicial activism can be seen. The controversy in Golaknath v State of Punjab can be seen as the rise of judicial activism in India. Article 13 of the Constitution has been widely interpreted by the Supreme Court in the case of Golaknath. In this dispute, it was decided that the Parliament has no power to amend the Fundamental Rights. This decision was changed by the 24th Amendment, but later it got new thrust from the concept of basic structure in the dispute of Kesavananda Bharati v State of Kerala. In fact, the principle of judicial activism in India came to the fore in the seventies when the right to be heard took its final shape in the case of SP Gupta v Union of India. This case became popular as the Judges Transfer Case. In this case, Judge Bhagwati is known as the father of the PIL. Assurances related to public interest have also played an important role in the development of judicial activism. 
Where something legally wrong is being done, any hurt is being caused or any threat is being given to any poor, helpless, incapacitated person or group of persons, who, because of his socially or economically disadvantaged status, finds himself unable to approach the court for relief, so any member of civil society can file an application under Article 226 under the High Court and under Article 32 under the Supreme Court through public interest litigation for seeking justice and judicial redress for the hurt person or group of persons. . Thus, judicial activism is not based on the present law.
Judicial activism is a sign of the fact that when the constitutional institutions become disorderly and autocratic under certain circumstances, the judiciary transcends its jurisdiction and redefines justice and the faith of the public remains in justice. In fact, justice does not mean only legal justice, but it also refers to social, economic and political justice as mentioned in the Preamble of the Constitution.
Public Interest Litigation and Judicial Activism
Public interest litigation can be considered as an instrument of judicial activism. Public interest litigation refers to litigation in the interest of the public, which was incorporated in the judicial process in 1970. Through this, an active role is played by the judiciary, which binds other organs of the state to perform their constitutional duties. If the executive and the legislature are compelled by this activism of the judiciary and are compelled to perform their duty, then this activism of the court preserves the power of democracy and the confidence of the people.
The court has given several important directions to the executive as well as the legislature on the basis of the public interest litigation. The Supreme Court has now realized its due role in the welfare state and is using tactics for this. The approach of judicial activism is in fact now serving as the dominant strategy for justice for the weaker sections of society. The idea of public interest litigation came from the Roman jurisprudence (Actio Popularis) which allowed every citizen to use the court in case of public wrongdoing. The development of Public Interest Litigation has contributed significantly in making judicial activism meaningful. 

In the last few years, many such decisions were made by the judiciary in order to fulfill its legal obligations in various scams prevalent in the politics, administration and socio-economic life of the country, which can remove the malpractices, inefficiency, corruption and injustice prevailing in the society and take various important decisions. The major decisions passed by the judiciary from the point of view of judicial activism are -

1. Notice to the industrial units of Agra and Mathura for the protection of the Taj

2. Instructions for cleanliness to the Delhi Municipal Corporation for the cleanliness of the city

3. Instructions regarding the shifting of factories and industrial units operating in residential areas located on the banks of the Yamuna in Delhi

4. Show cause notice to the government on election reforms

5. Necessary guidelines to the Election Commission to prevent criminalization of politics etc.

In Hussainara Khatoon v State of Bihar, the Supreme Court held that speedy trial is an essential and integral part of the fundamental rights, which are mentioned in Article 21 of the right to life and liberty. Many undertrials in Bihar were kept in different jails for many years without trial. The court ordered that all such prisoners, whose names have been produced before the court, should be released immediately. Speedy trial is a fundamental right, guaranteed under Article 21 of the Constitution. The Supreme Court considered it its constitutional duty to enforce this right of the accused persons. In such cases of litigation, the court gets an opportunity to give directions in the interest of the public by imposing public duties.

Indian Constitution and Judicial Activism
Articles 13, 32, 226, 141, 142 are of great importance in judicial activism. Article 32 guarantees fundamental rights in the Supreme Court. Article 13 gives the Supreme Court extensive power of judicial review. Using judicial review, the judiciary can check the constitutionality of the legislature and the executive. The High Court (Article 226) also has equal power in this regard. Article 141 indicates that the power of the Supreme Court is to declare laws. This power is not enacted, but in the course of its work of interpreting the law, it has the power to change the law. Article 142 enables the Supreme Court, in the exercise of its jurisdiction, to pass such orders that complete justice may be achieved in those circumstances in which, for whatever reason or reasons, the trial is pending. Through these articles, the Supreme Court as well as the High Courts play an important role in settling many social and environmental issues.
Environmental Protection and Judicial Activism
The efforts of the Supreme Court in controlling environmental pollution through PILs are really laudable, especially when in the present legal system, the legislature is lagging behind in meeting this shortcoming and the administration is not able to meet this challenge well. 
The Supreme Court, on the basis of a PIL in MC Mehta v Union of India 1986 (Shriram Food and Fertilizers case), directed the director of the company that the hazardous chemicals and gases may endanger the life and health of the workers and the people living in the neighborhood. Therefore, all necessary safety measures should be taken before reopening the plant.
In M.C. Mehta Vs Union of India, the petitioner tried to draw the attention of the court to the deterioration of the Taj Mahal due to environmental pollution (establishment and functioning of innumerable metal casting production factories and chemical hazardous industries around the Taj Mahal) through a PIL. Justice Kuldeep Singh, who is known as the Green Judge because of his judgment on pollution in this case, observed that 292 polluting industries, which are locally active in the area, are the main sources of pollution. He directed to replace natural gas as an industrial fuel and said that if they could not do so, they would have to stop working after December 31, 1997.
In Indian Council for Enviro Legal Action v Union of India, 1996, the Supreme Court held that if the fundamental rights of an individual are violated by the actions of private corporate bodies, the Court will not accept the argument that it is a 'state', which has the meaning assigned to it under Article 12 and hence action cannot be taken against it.  
If the court finds that the government or the authorities concerned do not take necessary action against them by law and the right to life of the citizens is violated, then it is the duty of the court to intervene. In this case, an environmentalist organization filed a writ petition before the court under Article 32 complaining about the plight of the people who live in the vicinity of industrial plants in India and requesting suitable remedial measures.
Bonded labor and judicial activism
In People's Union for Democratic Rights v/s Union of India ( Asiad Case), the court held that the state is bound to ensure compliance with the enacted labor laws so that the worker can get the right to live life with the dignity of human life enshrined in Article 21.
Protection Against Inhuman Treatment in Jail
In Sunil Batra v/s Delhi Administration, it was held that a writ of habeas corpus cannot be issued merely for the release of a person from illegal custody. But it can also be used to free the prisoners from inhuman and barbaric tyranny. Justice Krishna Iyer, in Veena Sethi v State of Bihar, declared that when the right of a prisoner is violated, this violation, whether under the Constitution or under other laws, can be used to exercise the power of petition for defense. The court was informed through a letter that some prisoners, who were deranged or neurotic at the time of trial but later declared sane, were not released due to the inaction of the state authorities. They were imprisoned for 20 to 30 years. The court directed the authorities to free them immediately.
Sexual Harassment of Working Women: Vishakha Guidelines
In Vishaka v/s State of Rajasthan, the Supreme Court made it clear that sexual harassment of working women amounts to infringement of the right to gender equality and the right to life and personal liberty. The Supreme Court has considered it a violation of Articles 14 and 21 of the Constitution. After analyzing all the offices or institutions, the Supreme Court laid down certain guidelines till a law is made for this purpose and declared under Article 141 that these guidelines shall be treated as law. The case provided relief to those lakhs of working women who were forced to remain silent while facing sexual remarks and harassment in their offices.
Ban on Smoking in Public Places
In a significant decision, the Supreme Court directed a ban on smoking in public transports and  other places including railways in all states and union territories. To issue this order immediately, the Center introduced an 'Anti-Smoking Bill' in Parliament.
Professional Ethics and Medical Treatment
In Parmanand Katara v/s Union of India, the Supreme Court held that it is the paramount duty of every member of the medical profession (private or official) to provide prompt medical treatment to every injured citizen without any procedural formalities. 
Child Security and Welfare
In M.C. Mehta v/s State of Tamil Nadu, it was held that children cannot be employed in match factories to avoid the risk of accidents under the Children's Employment Act, 1938. Such an employer would have to deposit a sum of Rs. 20,000 in a fund which shall be used for the child. In Lakshmi Kant Pandey v/s Union of India, a writ petition was filed on the basis of a letter. The letter revealed that Indian children adopted by foreign parents were working in several social organizations and voluntary agencies that indulged in wrong things and practices. Judge Bhagwati, while laying down the principles and rules, said, whether a child should be allowed to be adopted by a foreign parent or not, the determination should be made with the object of ensuring the welfare of the child. Under his authority, the government and various agencies were directed to follow these principles to deal with such cases. It was described as their constitutional obligation to ensure the welfare of the child under Article 15(3), 39(c) and (f).

Right to Life and Personal Liberty
In National Human Rights Commission v/s State of Arunachal Pradesh, the Supreme Court held that every citizen or non-citizen has the right to life and personal liberty under the guarantees provided by Article 21.
Fake Encounter
In People's Union for Civil Liberties v. Union of India, the court held that the fake encounter by the police was violative of Article 21. If it is proved that a person has been killed in a fake encounter by the police, the state can be ordered to pay compensation. The principle of universal immunity does not apply in such cases.
Some new examples of judicial activism
Cases of 2G spectrum and Commonwealth scams are clear examples of the use of public interest litigation to investigate the menace of corruption in the Indian administration. In both these cases, proceedings were initiated through public interest litigation at the behest of a public spirited person. On 2 February 2012, the Supreme Court took an unprecedented step and canceled 122 2G licenses issued by the government in 2008 to various telecom companies. 
In the Noida Land Acquisition Case, the Supreme Court quashed the acquisition of land by the Uttar Pradesh government. This land was acquired for industrial purposes, but it was given to builders to build apartments. The court ordered the land to be returned to the farmers from whom the land was acquired. Often the Supreme Court and various High Courts pass orders for CBI investigation in many cases. Under the law, this power is vested in the government. The Supreme Court has also played an important role in the 2002 Gujarat riots cases.
Criticism of Judicial Activism
The concept of judicial activism has been put under scrutiny by critics since its inception. The objection against judicial activism is that the judiciary unnecessarily interferes with the work of the legislature by bringing to the fore the inefficiency of the legislature and this can lead to constitutional crisis and the morale of the executive may decline from the decisive role of the Supreme Court. Critics further say that this interference sometimes creates difficulties in the way of the executive as to how to solve the new problem with a new strategy. It is anticipated that the judiciary will lose its prestige under this strategy. Lawyers have started complaining that public interest litigation is taking up much of the court's time and that a postcard is more important to the court than a fifty-page affidavit. It was further argued that the opening up of this new area of litigation will only lead to the collapse of the judicial system in India when the courts are full of data on pending cases. However, PILs in India do not support this apprehension. According to one opinion, the misuse of public interest has reached ridiculous limits. Public interest litigation is being filed in many cases, such as student and teacher strikes, lack of buses, lack of cleanliness in hospitals, irregularities in the stock market, dengue fever, examinations, admission in universities and colleges etc. 
In 1997, in a quest to guide the United Front government at the Center, a petition was filed against the Vajpayee government to void the no-confidence vote to form a coalition cabinet with the Congress. Many judges pay heed to PILs, so it is not just a sense of power and publicity. The liberalization of the right to be heard rule and the concept of social justice for the poor, oppressed and exploited sections of society also led the PIL judges to do justice in those cases. According to the critics, the court hears the petition to get the privilege. So many petitions in the majority should either not be filed or they should not be heard. Public interest litigation should be confined to those sections of society which cannot reach the court due to socio-economic constraints.