Research methodology

Our research process spans a four-month period for each ranking cycle. This includes collecting data, which is is a three-month process, and an additional month to process the data and establish the rankings. We rely on four main data sources and various criteria to create or update a ranking.


1. Firms that apply for a ranking

Submission Forms: The firm can complete a submission form where detailed information is requested on the firm’s performance in the last 12 months in the specific area being evaluated. The form requires the following information: 1. The top 10 cases in the last year; 2. The composition of the team (partners, associates); 3. Differentiation from competitors; 4. Clients and new business; 5. Significant changes in teams or staff; 6. A list of client referees with contact details.

The form is of utmost importance to our research: it provides firms with the opportunity to inform us why they should be ranked, justifying this by recapping their performance in that specific area over the last 12 months.

Interviews: We provide the opportunity for the firms to be interviewed by the editor in charge of the ranking. The meeting allows a further conversation about the firm’s performance, strategy and the state of the market. It is a confidential interview that allows the firm to expand further on topics that might not be revealed in the submission form.

2. Client Feedback

We currently have a consolidated database that contains many of the leading legal and financial advisors, general counsels and CFOs in each country. They are contacted by Leaders League to give their feedback on the area we are researching. In addition to this database, we also contact all clients listed in the referee forms by firms that submit (removing any contacts duplicated from our database).

An important point to note is that we do not contact clients on behalf of a specific firm but, instead, on behalf of our own organization and research. This is because: 1. We do not want to “meddle” in your relationship with your client, and 2. We believe that the feedback we receive when contacting in this way is much more spontaneous, leaving the client much more at ease to comment on the firms he/she has worked with, elaborate on their experience and share praise or criticism.

3. Peer Feedback

In both the submission forms and the interviews, we ask that firms recommend and comment on peers in the market. We also collect their opinions on lawyers they have worked with in other jurisdictions.

It is important to note that by no means do we take as “truth” what peers say about each other, understanding that there is an intrinsic bias to this type of feedback.

4. Qualified third-party review

This is a source unique to Leaders League due to its positioning. As Leaders League ranks different service providers – law firms, audit firms, investment banks, expert witness firms and many others – we are in touch with all of them during the research. This enables us to collect the opinion of a wide range of professionals depending on the area of expertise we are assessing, who are neither clients nor competitors of the ranked firm.

For example, when researching the best law firms in M&A, we take feedback from investment banks into account; when we are researching the best expert witness firms for arbitration, we obtain input from arbitrators, lawyers representing clients, and other key parties. Our reach gives us a wide view of the market to strengthen the validity of our rankings.


  • • Nature, complexity, size, volume, innovativeness and quality of the matters handled by the team
  • • Recognition and reputation of the firm in its market among clients, third parties and peers
  • • Team size and expansion, particularly at partner (or senior) level; track record of partners or client managers
  • • Prestige, diversity and internationalization of the firm’s client base

Would you like to be included in our rankings?

Contact our editorial team