Law is a big service-based business. Business, finance, taxation, litigation, corporate affairs, conflicts, patents, copyrights, antitrust, property, labor, arbitration, as well as administration, political, and social matters all require law expertise.

While there are other criteria to rank law firms—such as revenue per partner/lawyer, the number of lawyers, or year-on-year percent growth—annual revenue remains the most accurate, consistent, and easy to follow.

Here's a list of the top ten law firms in the world. All figures have been compiled from The American Lawyer's Global 200 ranked as of October 2018 and represent the fiscal year 2017.

Key Takeaways Revenues for the top two firms, Kirkland & Ellis and Latham & Watkins, each exceeded $3 billion for the 2017 fiscal year.

Kirkland & Ellis came out on top with $3.16 billion in revenue while Allen & Overy rounded out the list at number ten with $2.027 billion.

Eight of the firms are based in the United States, with two of them—DLA Piper and Hogan Lovelis—sharing headquarters in London.

Two of the top ten firms— Clifford Chance and Allen & Overy—are headquartered solely in the United Kingdom.

Kirkland & Ellis LLP

Kirkland & Ellis LLP takes pride in having a niche set of corporate clients served across the corporate, taxation, litigation, intellectual property, and restructuring fields. With approximately 2,000 lawyers on board, the U.S.-based firm's revenues stood at $3.16 billion, putting it at the top of the list.

Kirkland & Ellis was founded in 1909 in Chicago.

The firm has a number of high-profile clients including Boeing, Delta Airlines, Nike, and Verizon.

Latham & Watkins LLP

Headquartered in Los Angeles with offices in 14 countries and more than 2,400 lawyers on board, Latham & Watkins ranks second in terms of annual revenues, with a reported $3.06 billion.

The firm has a wide range of services from activism, to entertainment and media, to real estate, and white-collar defense.

Baker McKenzie

Founded in 1949 and headquartered in Chicago, Baker & McKenzie employs more than 4,700 lawyers with 77 offices across 47 different countries. Its reported revenues were $2.67 billion, making it the third highest on the list.

DLA Piper

One of the biggest global law firms with lawyers in more than 40 countries, DLA Piper came into existence after a mega-merger of multiple international law firms in 2005.

DLA Piper agreed to represent Paul Ceglia in 2010 in a lawsuit against Mark Zuckerberg, in which he claimed 84% ownership of Facebook.

Headquartered in London and Chicago, this firm came in fourth with annual revenues at $2.63 billion. It employs more than 3,600 lawyers throughout its offices, with practice areas in sectors such as education, government contracting, insurance, and technology.

Skadden, Arps, Slate, Meagher & Flom LLP

Skadden—as the firm is commonly known—was founded in 1948. With headquarters in New York, Skadden has 22 offices across the globe with an employee roster of more than 1,700 lawyers, and more than 50 practice areas.

Its reported annual revenues were $2.58 billion. The firm advises businesses, financial institutions, and government agencies worldwide.

Dentons

Dentons is the product of a flurry of mergers in the last half decade—the most recent being McKenna Long & Aldridge in April 2015. The firm boasts more than 8,600 lawyers and professionals in more than 125 locations in more than 50 countries.

Dentons ranked number six on the list with an annual revenue of $2.36 billion.

Clifford Chance LLP

Founded in 1987 through a merger, Clifford Chance is headquartered in London and has offices in 26 countries. Its roster includes approximately 2,100 lawyers.

According to the company's website, primary sectors include banks, healthcare, private equity, and transport and logistics. Its reported revenues were $ 2.09 billion.

Sidley Austin

Founded in 1866, Sidley—as it's more commonly known—is headquartered in Chicago. It reported revenues of $2.036 billion and over 1,800 lawyers in 20 offices around the world.

The firm focuses on corporate and finance, employment, regulatory and government affairs, and tax law.

Hogan Lovelis

Hogan Lovelis was formed as a result of a merger between Lovells LLP and Hogan & Hartson in 2010. The firm currently has more than 2,600 lawyers on its roster and reported $2.036 billion in revenue—putting it in ninth place.

The firm's main offices are in London and Washington, with a total of 49 offices around the world.

Allen & Overy

Headquartered in London with 44 offices in 31 countries with nearly 2,300 lawyers, Allen & Overy was founded in 1930. Its total revenues stood at $2.027 billion.

The Bottom Line

Law firms can have multiple practice areas, and for the world's top firms, expertise is required at both the local and global levels. The law firms listed above are successfully running their business across multiple practice areas, and have been effective in managing billion-dollar revenues consistently.