November 2025 / 5 Min Read

Aon Law Firm Symposium: Navigating the Risks and Rewards of Global Expansion through Merger

 

The recent Aon Law Firm Symposium in Nashville, Tennessee, welcomed over 500 esteemed guests from across the legal profession—a testament to the growing appetite for insight and connection among today’s law firm leaders. Featuring a range of panels supported by Aon Professional Services Practice’s Loss Prevention team and top legal minds, the event offered a forum for sharing expertise on the pressing challenges and opportunities faced by firms in today’s complex environment.

One of the many impactful panels, “Risks Involved in Going Global,” directly addressed questions we frequently hear from our clients and other law firms: What does it take to expand internationally, particularly through mergers? As more firms consider growth via geographic expansion and combination, this discussion couldn’t have been more timely. Below, we share in-depth highlights for those navigating a similar path.

Panellists: Andrew Clark, A&O Shearman, Laura Giokas, BCLP, Duncan Weston, CMS
Facilitated by: Sarah O’Neill, Aon UK Limited

Understanding the Motivations: Why Merge?

The panel began by examining the critical question: What drives a firm to seek merger as a growth strategy? Participants emphasised that any successful merger must centre on client benefits. Strategic expansion is not simply about growing for growth’s sake. Instead, a firm should only embark on this path when it can clearly articulate how the combination will improve its ability to serve both current and future clients.

Firms are often attracted to mergers because this approach delivers scale and operational resilience rapidly—opportunities that organic expansion or lateral hiring rarely match. A merger can provide immediate access to new markets, expanded expertise, and greater financial stability. As the panel noted, for firms seeking to change their competitive position quickly and meaningfully, large-scale merger may be the best route.

Choosing the Right Merger Partner

While aligning complementary practices is important, the panellists agreed that the most critical factor is the cultural fit between the merging firms. Mergers aren’t just business deals—they are more akin to a marriage, where shared values, long-term vision, and interpersonal chemistry play decisive roles.

Sometimes, pre-existing relationships among partners, such as having previously trained together, lay a sturdy foundation for collaboration and trust. When leadership teams resonate on a personal and professional level, the resulting firm is far more likely to achieve smooth integration and lasting cohesion. Cultural mismatches, by contrast, nearly always prove fatal to a merger’s success—and cannot be easily fixed after the fact.

Early Steps in Merging: Speed and Consensus are Crucial

Once the right partner is identified, swift action is imperative. The negotiation and agreement of key terms—the “heads of terms”—must happen early. Delays in this initial phase create risk and uncertainty that can undermine the entire process. The panel highlighted several critical issues to address upfront:

  • Governance structures: Establishing clear lines of authority
  • Compensation systems: Harmonising partner and employee remuneration
  • Tax and regulatory frameworks: Navigating local laws and requirements
  • Internal policies and procedures: Deciding which standards to adopt, and whether a “best of both worlds” approach is feasible
  • Financial models and capital structure
  • Conflict checking: Assessing potential client conflicts as early as possible, within regulatory limits

Success at this stage relies not just on internal leadership alignment but also on early engagement with trusted advisers—tax experts, M&A consultants, brand specialists, insurance brokers and public relations professionals—whose insights can be invaluable.

Pre-Merger Integration Planning: Building the Right Structure

As mergers cross borders and jurisdictions, integrating different operating models becomes more complex. The panellists shared their experiences navigating the challenges of rationalising performance metrics and compensation models across countries. An added complexity, particularly when merging with a U.S. firm, is that U.S. law firms often carry pension liabilities that require bespoke solutions.

Not all mergers follow the fully integrated model; some firms deliberately opt for looser structures for strategic reasons. Structures like the Swiss verein allow firms to scale quickly while sidestepping some integration challenges, such as unified financial systems or regulatory inconsistencies. In this model, the “glue” is often the strength of shared practice groups, rather than a single profit pool. However, while offering flexibility, these structures may confuse clients due to inconsistent branding, and they can slow decision-making by requiring consensus among autonomous entities. Nevertheless, some panellists noted that the absence of direct competition over profits can, in fact, promote harmony and smoother collaboration among member firms.

Due Diligence: The Foundation of a Successful Merger

A comprehensive due diligence process is the backbone of effective pre-merger planning. The panel underscored the necessity of examining:

  • Financial systems (billing rates, collection practices, cash vs accrual accounting)
  • Partner compensation arrangements (lockstep, modified lockstep, or “eat what you kill”)
  • Sources of client revenue, client dependency, and potential conflicts of interest
  • Professional liability insurance provisions, which should be agreed upon in the initial heads of terms whenever possible and, in which regard, the panellists noted they have been supported by their PI brokers
  • IT and data systems: While full integration from day one is ideal, early commitment to timelines and processes for technology alignment is critical

Proper due diligence helps both sides identify blind spots, manage client transition plans, and enables a smoother post-merger experience for all involved. The process must be approached from both firm’s perspectives, balancing competing priorities and building mutual trust.

Integration: Bringing Firms Together for Lasting Success

The ultimate test of a merger is successful integration—both operationally and culturally. The panel’s advice: foster connection and build trust immediately. Shared office spaces, whether by moving into new premises or reorganising existing ones, help break down barriers. Regular in-person engagement through conferences, town halls, and joint events accelerates relationship-building and collaboration.

Adopting the “best of both” approach for policies and technology, rather than imposing one firm’s systems on the other, demonstrates respect for both legacies and can ease transition pains. Throughout, frequent, transparent communication is vital to maintain morale and show that the merger delivers tangible benefits. Upholding transparency regarding decision-making and the rationale behind changes helps partners and staff buy into the new vision.

Avoiding Common Pitfalls: Lessons from Experience

The panellists candidly discussed why mergers sometimes fail. Delayed negotiations, slow announcement schedules, and leaks can dissipate value before the deal closes—currency fluctuations, partner defections, and reputational risks can all undermine progress. An inflexible approach to financial alignment may cause irreconcilable divisions; one practical recommendation is to restructure internally before merging, ensuring a smoother fit on day one.

But perhaps the greatest risk is neglecting the importance of trust and shared culture. When the people at the top aren’t truly aligned—whether in values, ambition, or decision-making style—operational challenges multiply and the merger’s odds of success plummet. Both sides must commit fully to the partnership from the outset.

Optimism for the Future: Insights from Successful Mergers

Despite the complexities, the panel was ultimately optimistic about global expansion through mergers. Their own experiences—sometimes forged in the fires of past missteps—have resulted in stronger, more resilient firms. They remain convinced that with the right motivation, partner alignment, rigorous planning, and an unwavering focus on clients, international expansion is not just possible, but a path to enduring success.

As more law firms explore combining strengths in an increasingly interconnected world, the wisdom shared at the Symposium serves as a valuable guide. We hope these insights assist you as you consider your own growth trajectory.

If your firm is contemplating merger, international expansion, or a new approach to growth, please reach out to our team. We are here to support you every step of the way.

Aon’s Thought Leader for more information:

Jennifer Millar
EMEA Professional Services Industry Vertical Leader

About Aon
Aon plc (NYSE: AON) exists to shape decisions for the better — to protect and enrich the lives of people around the world. Through actionable analytic insight, globally integrated Risk Capital and Human Capital expertise, and locally relevant solutions, our colleagues in over 120 countries provide our clients with the clarity and confidence to make better risk and people decisions that protect and grow their businesses. The information contained herein and the statements expressed are of a general nature and are not intended to address the circumstances of any particular individual or entity. Although we endeavour to provide accurate and timely information and use sources that we consider to be reliable, there can be no guarantee that such information is accurate as of the date it is received or that it will continue to be accurate in the future. No one should act on such information without appropriate professional advice after a thorough examination of the particular situation. Follow Aon on LinkedIn, X, Facebook and Instagram. Stay up-to-date by visiting the Aon's newsroom and sign up for News alerts here. ©2025 plc. All rights reserved. This article has been compiled using information available to us up to 06/11/2025. Aon UK Limited is authorised and regulated by the Financial Conduct Authority. Aon UK Limited is registered in England and Wales. Registered number: 00210725. Registered Office: The Aon Centre, The Leadenhall Building, 122 Leadenhall Street, London EC3V 4AN. Tel: 020 7623 5500