Lee & Ko

An undisputed premier firm, Lee & Ko holds steady in the rankings as a fool-proof choice for its impressive roster of offshore and onshore clients. Its renowned finance practice wins plaudits from peers and clients that acknowledge its frequent role in representing lenders. The firm was elevated this year into the ‘Outstanding’ tiers for labour and employment and real estate. Lee & Ko’s traditional dominance in debt capital markets helped it maintain a steady flow of debt deals. Managing partner Yong Seok Ahn is recognised for his corporate and competition expertise.  

The firm has continued to evolve its practice areas through strategic hiring and internal changes. In the dispute resolution sector, Lee & Ko strengthened its team with key hires, including partners Young Su Kang, Tai Han Ha and Eun Pyo Hong in March 2025, and Eun Young Park in October 2024. The competition practice was bolstered by the addition of senior advisor Moo Jin Choi from the Korea Fair Trade Commission in March 2025. 

The firm has bolstered its intellectual property practice with a key partner-level hires in the past year. Hankil D. Kang joined the firm as a partner in May 2024, from Bae, Kim & Lee. These strategic appointments underscore Lee & Ko's commitment to expanding its IP capabilities, particularly in healthcare-related fields. 

Client feedback 

"At Lee & Ko, they demonstrated a clear and thorough understanding of our business and its unique characteristics. Rather than providing general legal advice, they offered precise, tailored answers that addressed the specific issues we faced. Moreover, they provided clear and practical guidance on how to resolve those issues effectively, helping us make well-informed decisions at each stage. Their ability to grasp the core of our business and deliver relevant, actionable solutions was especially valuable." – Competition/antitrust 

"Lee & Ko actively seeks to understand the company's business areas and provides effective solutions based on this understanding." – Competition/antitrust 

"They are professional and excellent." – Competition/antitrust 

"Lee & Ko demonstrates strong expertise across a wide range of regulatory and compliance matters, particularly in complex areas such as competition law and corporate investigations. 
The firm is known for its depth of legal analysis, clear strategic advice, and ability to provide practical solutions tailored to the client’s business context. Their responsiveness and collaborative approach make them a reliable partner in sensitive and time-pressured situations. Overall, Lee & Ko combines legal excellence with commercial awareness, which makes their counsel both actionable and effective." – Competition/antitrust 

"They have top-tier experts and professional legal support." – Competition/antitrust 

"Lee & Ko conducted a thorough review with a high level of expertise and presented various alternatives." – Competition/antitrust  

"Lee & Ko combines deep legal expertise with a strong understanding of the Korean regulatory and business landscape. The firm is highly responsive and practical and consistently delivers high-quality advice across complex matters. Their client-focused approach and professionalism make them a trusted partner in both domestic and cross-border issues." – Competition/antitrust 

"They have great expertise and are easy to communicate with." – Competition/antitrust 

"The law firm holds business-specific professional expertise." – Competition/antitrust 

"As OK Financial Group was recently designated as a large business group by the KFTC, it is undergoing its first investigation by the KFTC. In this unfamiliar situation, Lee & Ko has been providing proactive and effective support in responding to the investigation. Moreover, they have been offering practical advice to help mitigate future risks related to fair trade compliance." – Competition/antitrust 

"Lee & Ko demonstrated exceptional diligence in investigating the factual basis of our case. Their thorough approach to fact-finding appears to have been a critical factor in the successful outcome of the litigation. Effective legal representation in damages lawsuits requires a comprehensive understanding of all relevant circumstances, and Lee & Ko excelled in this aspect of their service. The firm appears to have developed and executed an effective litigation strategy based on their thorough fact investigation. In damages lawsuits, establishing or refuting the elements of liability (duty, breach, causation and damages) requires strategic planning and execution." – Corporate and M&A 

"Their answers are always reliable and prompt." – Corporate and M&A 

"Lee & Ko is a premier Korean law firm with a well-earned reputation for legal excellence, strategic insight, and client dedication. The firm’s strength lies in its ability to deliver sophisticated, commercially sound advice across a wide range of complex legal issues, particularly in cross-border disputes and international arbitration. One of the most commendable aspects of Lee & Ko is its deep bench of highly skilled professionals who work seamlessly across practice areas. The firm demonstrates a clear understanding of client objectives, and its advice consistently reflects both technical precision and practical judgement." – Dispute resolution 

"Lee & Ko has a deep understanding of trademark law and provides practical, business-orientated advice. Their team is highly responsive, detail-orientated, and reliable in managing both domestic and international trademark matters." – Intellectual property 

"They analysed the technology in detail and reviewed the risks with suggested alternatives." – Intellectual property 

"Lee & Ko is one of the most prestigious law firms in Korea, and its diverse range of expertise enables effective communication among specialists from various fields. This collaboration ensures that clients receive accurate, comprehensive responses in a timely manner." – Intellectual property 

Jeong Yoon Choi 

"Jeongyoon is a highly knowledgeable and reliable expert in Korean competition law. She has a clear ability to analyse complex regulatory issues and translate them into practical, business-orientated advice. Her communication is always precise, timely, and solution-focused, which makes her an effective partner in both advisory and contentious matters. Her calm and thoughtful approach builds trust with clients, and her deep understanding of KFTC practice adds significant value to strategic decision-making." 

Byong Ki Chung 

"He demonstrates exceptional legal expertise and thorough understanding of complex issues. He is highly responsive and communicates clearly, ensuring that clients are always well-informed. His practical approach and attention to detail enable him to deliver effective solutions tailored to the client’s needs. Additionally, his professionalism and dedication build strong trust and confidence in his work." 

Sanghoon Han 

"Sanghoon is a highly capable and practical lawyer, particularly skilled in navigating complex construction disputes. What sets him apart is not just his deep knowledge of international arbitration and construction law but also the clarity and focus he brings to fast-moving, high-stakes matters. He has a unique ability to break down technically and legally complex issues into clear, manageable strategies – always keeping the big picture in mind while paying close attention to detail. In our experience, Sanghoon is exceptionally responsive. He’s consistently available, quick to grasp evolving issues, and solution-orientated in a way that gives clients real confidence. Even under tight deadlines or with complicated procedural developments, he remains calm, clear-headed, and constructive. Equally important, he’s a pleasure to work with. His collaborative and down-to-earth style makes it easy to align quickly on strategy, even across jurisdictions and teams. That combination of legal acumen, responsiveness, and approachable professionalism is rare – and extremely valuable in high-stakes cross-border matters." 

Jang Hyun Ka 

"He has been serving as the main handler in the current KFTC investigation, providing highly proactive and hands-on advice. Despite the fast-moving and urgent nature of the situation, he has responded swiftly and delivered effective, well-calibrated counsel based on his extensive experience." 

"He excels in communication with clients and responds quickly and proactively." 

Ji Yeon Kim 

"She does a thorough fact investigation and strategic case management." 

“She successfully completes the given mission with positive thinking and unyielding will.” 

Jaewoo Kwak 

"Jaewoo provides prompt and clear advice on trademark matters. He is professional, attentive to detail, and offers practical solutions tailored to our business needs." 

"He responds positively to new questions without panicking." 

"Jaewoo is the type of person you enjoy working with, both professionally and personally. He has been instrumental in applying his expertise in intellectual property across various fields. His exceptional knowledge and dedication have earned him the distinction of being named Attorney of the Year in Korea for consecutive years." 

In Seon Lee 

"He is aggressive, professional, and kind." 

Miji Lee 

"With over 20 years of experience in the field of competition law, her deep knowledge and practical expertise have been an invaluable asset to our company. Her extensive understanding of both legal regulations and industry practices allowed her to provide advice that was not only legally sound but also highly relevant to the realities of our business operations. Her ability to anticipate potential regulatory risks and suggest proactive, practical solutions helped us navigate complex situations with confidence. Her insights into subcontracting regulations, fair trade practices, and competition compliance significantly contributed to strengthening our internal systems and decision-making processes. Thanks to her guidance, we were able to manage sensitive business matters more effectively and minimise legal exposure in critical areas." 

Hyun Ah Song 

"She always provides positive speech and friendly answers." 

Jeong-Ho Sun 

"He understands even the most complex issues very well from the company’s perspective and always provides the best advice, which is why we keep turning to him. He has particularly strong insights into fair trade matters and is highly regarded in other areas of laws and regulations as well." 

"He has great expertise, is easy to communicate with, and has great relationships." 

"He has good communication with clients and expertise in competition law." 

Work highlights 

Represented DB Insurance as appellant in the High Court appeal reversing the district court’s ruling that an independent-contractor sales-team leader was an employee entitled to severance pay, establishing a key 2024 precedent on contractor-versus-employee classification under the Labor Standards Act. 

Represented Kumho Tire as respondent in the High Court labour dispute brought by newly direct-hired workers seeking retroactive employee-stock benefits for the period when they had been unlawfully dispatched, securing dismissal of all claims and setting a 2024 precedent that discretionary ESOP benefits are not subject to retroactive employer liability. 

Represented Samsung Electronics and its senior officers as appellants in the High Court appeal reversing their district-court convictions for negligent manslaughter and fire-safety violations arising from a fatal CO₂ leak at the client’s facility, establishing a 2024 precedent on causation and the scope of officers’ duties under Korea’s Serious Accidents Punishment Act. 

Key clients 

DSM-Firmenich Group, Hyundai Motor Company 

Work highlights 

Represented OCI Company as defendant in the patent-infringement suit brought by Wacker Chemie AG concerning polycrystalline-silicon manufacturing technology, invalidating the asserted patent at the Supreme Court for failure to satisfy the description requirement and setting a key precedent on parameter-invention disclosure standards. 

Represented Tri Chemical Laboratories as patentee in the validity challenge brought by Versum Materials Korea concerning Tri Chemical Laboratories’ hafnium-precursor patent, persuading the IP High Court to uphold the patent’s inventiveness and validity despite an adverse precedent, thereby preserving Tri Chemical Laboratories’ dominant position in the high-k dielectric precursor market. 

Key clients 

Chemtronics, Fuji Electric, LG Chem, SharkNinja 

Work highlights 

Represented the CEO of SK Chemicals as defendant in the criminal prosecution arising from South Korea’s humidifier-steriliser tragedy, securing a Supreme Court acquittal in December 2024 that reversed the appellate court’s guilty verdict and definitively rejected criminal liability for product-defect injuries. 

Represented Korea Electric Power Corporation and Korea Hydro & Nuclear Power as claimants in the ICC arbitration against Westinghouse Electric Company concerning post-licence restrictions on the export of Korean-designed APR-1400 nuclear reactors, securing a confidential January 2025 settlement that removes all asserted technology-transfer and US export-control barriers and clears the way for Team Korea’s global reactor sales. 

Key clients 

Ilsan Grand Bridge, Korean Airlines, Z Intermediate Global Corporation 

Work highlights 

Represented Air Incheon as buyer in the acquisition of Asiana Airlines’ entire cargo business from Korean Air Lines – a divestiture mandated by the European Commission and Japan Fair Trade Commission as a condition for approving the Korean Air-Asiana merger – guiding Air Incheon from preferred-bidder selection through the unprecedented re-licensing of all route and operating permits across the US, China, Hong Kong, Germany, Austria, Italy, Belgium, Kazakhstan, the UK and Thailand, while satisfying EU Commission purchaser-approval and monitoring-trustee requirements. 

Represented Macquarie Korea Infrastructure Fund as buyer in the first-ever institutional acquisition of a Korean data centre, purchasing 100% of Hanam Data Center through its SPV Green Digital Infra, and navigating complex construction succession, cybersecurity and data-protection compliance to close the precedent-setting transaction. 

Key clients 

Koramco Asset Management, Rifa Asset Management 

Work highlights 

Represented the Korean Bar Associations as appellants in their successful appeal against the Korea Fair Trade Commission’s (KFTC)decision that sanctions banning attorneys from using the Law Talk legal-tech platform violated the Monopoly Regulation and Fair Trade Act, persuading the Seoul High Court on October 24, 2024 to overturn the KFTC ruling and uphold the Bar Associations’ regulatory authority under the Attorney-at-Law Act. 

Represented Yogiyo as defendant in the criminal prosecution brought by the Prosecutor’s Office concerning Yogiyo’s “lowest price guarantee” most-favoured-nation (MFN) pricing policy, securing a complete acquittal in the first instance, appellate and Supreme Court proceedings that established a precedent on intent standards for platform MFN clauses under Korea’s Monopoly Regulation and Fair Trade Act. 

Key clients 

Broadcom, Naver Corporation, Novo Holdings, One store 

Work highlights 

Represented a syndicate of 40 Korean lenders and the mandated lead arrangers (Kiwoom Securities, NH Investment & Securities, NongHyup Bank and Kookmin Bank) as lenders in the acquisition financing of IMM Private Equity’s W1.7 trillion ($1.2 billion) buyout of Korea’s leading waste-management company, Ecorbit, from KKR and Taeyoung Group, Korea’s largest M&A transaction of 2024. 

Represented Standard Chartered Bank (Hong Kong) as the Korean counsel in the secured financing of HMM’s acquisition of nine second-hand bulk carriers through a $270 million bareboat-charter hire-purchase structure, structuring a novel nomination arrangement that allowed HMM to take delivery with its own funds and later be reimbursed via the loan.