1. Core Legal Answer & Context: Judicial activism refers to the judiciary's proactive role in interpreting the Constitution and laws to achieve social justice, protect fundamental rights, and hold the executive and legislature accountable. It often involves the courts stepping into areas traditionally considered the domain of the other two branches. The principle of Separation of Powers, a cornerstone of the Indian Constitution and part of its Basic Structure, advocates for distinct functions and powers for the legislature, executive, and judiciary to prevent concentration of power and ensure checks and balances.

Inconsistency Argument: Critics argue that judicial activism, particularly through Public Interest Litigations (PILs), issuing detailed guidelines (e.g., Vishaka guidelines), or monitoring executive actions, can lead to judicial overreach. When courts issue directions that resemble policy-making or legislate where there is a vacuum, they are seen as encroaching upon the legislative and executive domains. This blurring of lines can undermine the distinct roles envisioned by the Separation of Powers, potentially leading to a less accountable judiciary making decisions that should ideally be debated and decided by elected representatives or implemented by the executive.

Consistency Argument (or Necessary Intervention): Conversely, proponents argue that judicial activism is not inherently inconsistent but rather a necessary corrective mechanism, especially in a developing democracy like India. It often arises when the executive or legislature fails to perform its duties, protect fundamental rights, or address pressing social issues. In such situations, the judiciary steps in to fill the vacuum, enforce constitutional mandates, and ensure justice. The Supreme Court's powers under Articles 32, 142, and 226 allow it to do 'complete justice' and enforce fundamental rights, which sometimes necessitates proactive intervention. This is seen as upholding the spirit of the Constitution, particularly the Basic Structure, which includes the rule of law and fundamental rights.

2. Relevant Statutes and Sections:

• Article 50: Directs the State to separate the judiciary from the executive.
• Articles 13, 32, 226: Provide for judicial review and enforcement of fundamental rights, forming the basis of judicial activism.
• Article 142: Grants the Supreme Court extraordinary power to pass any decree or order necessary for doing 'complete justice' in any cause or matter pending before it.
• Basic Structure Doctrine: Enunciated in Kesavananda Bharati, it includes the Separation of Powers as a fundamental feature.

3. Important Landmark Cases:

• Kesavananda Bharati v. State of Kerala (1973): Established the Basic Structure Doctrine, including the Separation of Powers, as an unamendable feature of the Constitution. This case provides the theoretical framework for evaluating judicial activism.
• S.P. Gupta v. Union of India (1981) (Judges' Transfer Case): Widened the scope of locus standi, paving the way for Public Interest Litigation (PIL) and significantly boosting judicial activism.
• Vishaka v. State of Rajasthan (1997): In the absence of specific legislation, the Supreme Court laid down guidelines to prevent sexual harassment at the workplace, effectively legislating to fill a vacuum. This is a prime example of judicial activism that some argue crosses into the legislative domain.

4. Clear Conclusion: While judicial activism can sometimes appear to blur the lines of the Separation of Powers, it is not necessarily inconsistent with it. In India, it has largely evolved as a response to legislative inaction or executive failures, serving as a vital check and balance to uphold constitutional values and protect citizens' rights. The key lies in judicial self-restraint and a clear understanding of institutional boundaries. When exercised judiciously, activism strengthens democracy; when it oversteps, it risks undermining the distinct roles of the other branches. The challenge is to maintain a dynamic balance where each branch respects the others' domains while collectively working towards constitutional goals.