In common law jurisdictions, the principle of severability has a rich heritage. Its development has been fuelled by diverse considerations, such as the intention of lawmakers, the constitutionality of laws, and the promotion of legal order. Originally, it emerged from the English common law, which allowed judges to retain the parts of a law that were valid while striking down those that were not.

The United States' contribution to the severability doctrine was showcased in the landmark case of "McCulloch v. Maryland". The U.S. Supreme Court was able to safeguard certain institutions by discarding state laws that were incompatible thanks to the successful execution of a plan.

Legal systems in today's world rely on the doctrine of severability to ensure the enforceability and legality of legal documents, laws, and contracts. This essential tool has demonstrated its usefulness time and time again. Its origins began during the Civil Rights Era and gained further clarification in instances involving racial segregation. Despite its historical roots, severability has been used in contemporary situations such as those concerning healthcare and intellectual property.

The intricate complexities of the Affordable Care Act's individual mandate were effectively addressed by the U.S. Supreme Court through the doctrine of severability in the case "NFIB v. Sebelius." This critical asset is now more readily available to assist the legal system in navigating this issue.

Concept of Doctrine of Severability
If a statute possesses an offending part, it is only that part that is considered void as per the doctrine of severability, and the rest of the statute remains valid. Voiding only the specific offending portion of a statute is the mandate of Article 13, rather than the statute as a whole.

The Supreme Court has expressed this principle succinctly in the following manner:

1. If the valid and invalid provisions cannot be separated from one another then the entire Act becomes invalid.
2. If the valid and invalid portions from a single scheme which are intended to be operative as a whole then the invalidity of a part results in invalidity of the whole.
3. If after excluding the invalid portion what remains cannot be enforced then the whole Act becomes invalid.
4. If the invalid part is separate in its operation from the other parts, then only the invalid part is so declared. Operative it remains as the rest is severed.
5. The effect of the application of the doctrine is that the Act is void in parts. That portion which is not void, survives.

In RMDC v. UOI, AIR 1962 SC 594, the Supreme Court states that the doctrine of severability is a matter of substance and not of form.

In 1876, a notable application of the doctrine appeared in the case of Maxim Nordenfelt Guns and Ammunition Company Ltd v. Nordenfelt. Despite nullifying one section of the agreement, the court permitted the remaining portion to proceed once separated from the offending section.

Foreign Case Laws highlighting the Doctrine of Severability
The doctrine of severability has been applied in numerous legal cases across various jurisdictions. The application of this doctrine has been illustrated in various contexts through notable case laws. A few examples are given below:

United States v. Booker: In this case in 2005, the Supreme Court put the Sentencing Guidelines of the United States under scrutiny. The concept of severability was explored, ultimately resulting in a ruling that deemed the Guidelines unconstitutional. This was due to the imposition of mandatory sentencing ranges, which were found to violate a defendant's Sixth Amendment right to a fair jury trial. However, instead of invalidating the entire Guidelines system, the Court used severability to excise the mandatory provisions, making the Guidelines advisory rather than mandatory.

National Federation of Independent Business v. Sebelius (2012):
Using its Commerce Clause power, the U.S. Government attempted to establish a rule requiring the purchase of health insurance. However, the Court severed this mandate and allowed the remaining parts of the rule to remain, stating that the government cannot force individuals to buy anything against their will. Thus, the law requiring health insurance was deemed unconstitutional.

The mandate that required people to have insurance was deemed permissible by the Court as long as the government treated it as a tax. This means the government can enforce a penalty on individuals who do not obtain insurance, rather than forcing them to purchase it. It presents a bit of a decision, either pay for insurance or pay the tax.

Ayotte v. Planned Parenthood of Northern New England (2006): The purpose was to evaluate a statute in New Hampshire. The statute required minors to inform their parents before undergoing abortion. However, the Court found a lack of health exception relating to pregnant minors, leading to its unconstitutionality. Notwithstanding, instead of invalidating the entire law, the Court exercised severability, permitting the law to endure if an inclusion of the health exception was made.

Roe v. Wade (1973): Severability was first recognized by the U.S. Supreme Court in 1973's Roe v. Wade case dealing with abortion rights. Women were granted the choice to have an abortion, while states were granted power to regulate procedures to a degree. Thus, banning abortion is not absolute and has legally been allowed in certain situations.

Zivitofsky v. Kerry (2015): The United States Congress passed a law in 2002 that agreed U.S. citizens born in Jerusalem can have "Israel" stated as their place of birth on their passports. However, the U.S. Government specially the State Department decided against implementing this law. Their argument was that it could intervene with foreign policies in the Middle East. Jerusalem's status remains a divisive issue in the Israeli-Palestinian conflict, thus, the State Department attempted to avoid it.

In regards to the place of birth on his passport, Menachem Zivotofsky, a Jerusalem native, took legal action. The case eventually reached the Supreme Court and concluded in 2015 when the Court deemed the President as having sole authority for acknowledging foreign governments. Congress was unable to mandate that the State Department include "Israel" on the passports of those born in Jerusalem. The decision was perceived as a significant one that highlighted the division of powers between the Executive and Legislative branches of the U.S. government in foreign policy matters.

Salman Rushdie v. Penguin Books: Salman Rushdie and Penguin Books clashed legally in 1987 over the release of "The Satanic Verses," a moment in history that tested boundaries of free speech and questioned the printing of contentious texts. This event was pivotal, marking a turning point in the world of literature. This case demonstrated the implementation of severability. Specifically, severability was a relevant doctrine in considering whether some parts of the book could be deemed objectionable while other parts were valid under the principles of freedom of speech. This incident remains an exceptional example of how a legal context can apply the doctrine of severability towards literary works that spark controversial reactions.

State of Texas v. United States: Challenging the Deferred Action for Parents of Americans and Lawful Permanent Residents (DAPA) program and the expansion of the existing Deferred Action for Childhood Arrivals (DACA) program in this case, Texas and several other states claimed that President Obama's executive actions were unconstitutional. The doctrine of severability was a factor in the legal debates.

In questioning whether or not to accept the more contentious parts of the executive orders surrounding immigration (DACA expansion and DAPA), the court deliberated over whether or not these policies could be disentangled from the more conventional parts of the plan. Were these policies judged to be illegal, the legal concept of severability could be implemented so that the court could decide if the other policies should still be allowed or if the entire set of actions should be null and void.

The constitutionality of DAPA and the DACA expansion were not conclusively determined as the U.S. Supreme Court was evenly divided on the matter in this case. Consequently, the doctrine of severability remained uncertain, and no definite ruling was set regarding its application to executive actions in immigration matters. Hence, the case did not establish a definitive precedent either for or against this principle.

Indian Case Laws highlighting the Doctrine of Severability
The doctrine of severability is recognized and applied in Indian law as well. Here are some Indian case laws that highlight the application of this doctrine:

• I.R. Coelho (Dead) by LRs. v. State of Tamil Nadu (2007): In this significant case, the Indian Supreme Court addressed the doctrine of severability concerning the Ninth Schedule of the Indian Constitution. The Ninth Schedule was initially created to protect land reform laws from judicial review. However, over time, several laws unrelated to land reforms were included in the Ninth Schedule. The Court ruled that laws inserted in the Ninth Schedule after April 24, 1973, were not immune from judicial review and could be subject to challenge. This case illustrated the application of the doctrine of severability by allowing the separation of laws in the Ninth Schedule, which were beyond the protection provided by the Constitution.
   
• Indra Sawhney v. Union of India (1992): In this case, commonly known as the "Mandal Commission case," the Supreme Court of India addressed the constitutionality of job reservations based on caste. The Court upheld the idea of reservations for socially and educationally backward classes but struck down the government's notification extending reservations to the "creamy layer" within the backward classes. This decision demonstrated the application of severability by separating the valid part (reservations for backward classes) from the invalid part (reservations for the creamy layer).
   
• Ashoka Kumar Thakur v. Union of India (2008): In this case, the Supreme Court of India considered the constitutionality of the Central Educational Institutions (Reservation in Admission) Act, 2006, which provided for reservations in educational institutions. The constitutionality of private institutions was questioned under the Act. It focuses on those not backed by public funding with specific emphasis on Scheduled Tribes, Scheduled Castes, and Other Backward Classes (OBCs). Nonetheless, the Act's validity was upheld. The doctrine of severability was applied to strike down the specific provision while preserving the rest of the Act. In April of 2008, the Indian Government's 27% OBC quotas for Government-funded institutions were upheld by the Supreme Court. The Court was clear in its affirmation that the "Creamy Layer" ought to be excluded from reservation policy and that private institutions shouldn't be included either.
   
• Rajbala v. State of Haryana (2015): In this case, the Supreme Court dealt with the issue of educational qualifications required for contesting Panchayat elections in Haryana. Struck down were the particular provisions that deemed those with certain criminal records unable to run for office; however, the Court found the stipulation of minimum educational requirements for candidates justifiable. This case showcased the application of the doctrine of severability in legislative provisions.
   
• AK Gopalan v. State of Madras: The Preventive Detention Act's Section 14 was deemed unconstitutional in the AK Gopalan v. State of Madras case, as it violated Article 14. The Court ruled that the Act's object will remain the same. Only the challenged provision will be removed, not the entire Act, when Section 14 is struck down. In the case of DS Nakara v. Union of India, a similar observation was made.
   
• Bombay v. FN Balsara: Bombay Prohibition Act, 1949 did not require invalidation in its entirety as held by the State of Bombay v. FN Balsara case due to only certain provisions violating the law.
   
• 42nd Amendment: The Supreme Court declared Sections 4 and 55 of the 42nd Constitutional Amendment Act invalid, for being beyond the amending powers of the Constitution but held the rest of the Act valid.
   
• Kihoto Hollohan v. Zachillu: In Zachillu v. Kihoto Hollohan, the Court declared that paragraph 7 of the Tenth Schedule was unconstitutional due to its violation of Article 368(2). However, the Court did uphold the rest of the Tenth Schedule's validity. Paragraph 7 of the Tenth Schedule barred any court jurisdiction in the case of disqualification of a member.

Conclusion:
Promoting the continued effectiveness of a law or agreement, the doctrine of severability enables courts to nullify particular provisions or obligations within a legal context. The jurisdiction and nuances of each case will dictate the specific application and outcomes of this doctrine. The remaining valid portions of a law or contract have been able to be preserved utilizing this technique in a variety of legal situations. The doctrine is put in place to safeguard individuals' rights and interests while still upholding the rule of law amid constitution violations.

References:

1. https://byjus.com/free-ias-prep/doctrine-of-severability/
2. Interpretation of Statutes, P. Krishnaswamy, Asia Law House