Subsequently, she was awarded a Rhodes Scholarship to read for the BCL at the University of Oxford (2000)[10] and the Gammon Fellowship to pursue the LL.M at Harvard Law School (2001).
In the year 2019, in an interview with CNN Fareed Zakaria, Guruswamy revealed that she was in a relationship with lawyer Arundhati Katju, with whom she convinced the Supreme Court in 2018 to decriminalise Section 377, saying that the victory was not just a professional benchmark but also a personal win.
In April 2016, Guruswamy along with a team of lawyers including Arundhati Katju and Saurabh Kripal filed a petition on behalf of five LGBT petitioners led by Navtej Singh Johar challenging the constitutionality of Section 377 of the Indian Penal Code, 1860.
[12] Guruswamy also appeared on behalf of petitioners from the Indian Institute of Technology, Delhi and in the landmark judgment, the 5-judge Constitutional bench of the Supreme Court read down Section 377 as not applicable to consenting adults.
She had also appeared for Shyam Benegal the film maker in the Supreme Court in the case of Suresh Kumar Koushal v. Naz Foundation (2013).
[13] In a significant decision, the Supreme Court held, inter alia, that bureaucrats are not bound to follow oral orders from Government officials and must rely on written orders, that a Civil Services Board consisting of senior bureaucrats must be formed at the Centre and State level to look into matters of postings and transfers.
[14] Guruswamy represented an intervenor, the Azim Premji Foundation, in the case of Society for Unaided Private Schools of Rajasthan v. Union of India pertaining to the constitutionality of Section 12(1)(c) of the Right of Children to Free and Compulsory Education Act, 2009.
[16] Guruswamy was a part of the team of lawyers that successfully litigated against Salwa Judum in the landmark case of Nandini Sundar v. State of Chhattisgarh [(2011) 7 SCC 547].
[17] Salwa Judam was the practice of deploying tribal youths as Special Police Officers in the fight against the Maoist insurgency and ordered their immediate disarming.
[18] In the Augusta Westland corruption case, wherein middlemen and Indian officials received kickbacks in a deal to purchase helicopters, Guruswamy represented former Air Chief Marshal S.P.
[27] In January 2019, her name featured in Foreign Policy's 100 Global Thinkers List, along with other prominent personalities such as Michelle Obama, Kofi Annan and Jeff Bezos.
Her most recent publications include essays on Constitution-Making in South Asia, in Handbook on Comparative Constitutional Law (Edward Elgar, Forthcoming (2019), short piece on the Aadhar decision in the American Journal of International Law (2018) and 'Crafting Constitutional Values: An Essay on the Supreme Court of India', (An Inquiry into the Existence Of Global Values, Hart Publishing/Bloomsbury (2015).