If you're not worried about the Big Four, you should be. That's the message many legal industry watchers have been sharing with law firm leaders, and one that has taken on added resonance with last week's announcement that Deloitte UK will ally with US immigration law firm Berry Appleman & Leiden (BAL).

"You can see through this move that the Big Four organisations are continuing to move down the path they've been pretty clear about," said Stephen Poor, chair emeritus of Seyfarth Shaw.

The Big Four occupy just one corner of the burgeoning market for alternative legal services providers, which now accounts for $8.4bn in legal spending, according to a 2017 study by the Georgetown University Centre for the Study of the Legal Profession in conjunction with Oxford University and Thomson Reuters.

That's a tiny fraction of the approximately $700bn spent on legal services worldwide annually. But the Big Four in particular – given their size and track record serving major clients – are in a strong position to continue to encroach on traditional law firms.

They also have a motive to expand, according to Eversheds Sutherland co-CEO Lee Ranson.

"It's coupled with increasing pressure on the international scene, with their audit functions getting squeezed on profits and regulations," he said. "They're seeing law as being much better suited to sitting alongside their consultancy operations."

On its surface, Deloitte's decision to invest in immigration law doesn't amount to an incursion into the core terrain of international law firms. Immigration is a niche practice, one that is not part of the portfolio of most full-service global firms. But the move still sends a clear signal about Deloitte and its fellow accounting firms' intent.

The arrangement with BAL involves an alliance between Deloitte UK and the 100-lawyer firm's US operations, while Deloitte will acquire the firm's international operations in eight countries. Deloitte has already indicated its interest in the area, by entering into a similar alliance in 2014 with Canadian immigration law firm Guberman Garson.

"There's a lot about the immigration practice that makes sense: the ability to think about efficiencies, technology and high volume," Poor said. "Those are characteristics that play right to the Big Four's strengths."

Looking for new niches

Several key obstacles stand in the way of the Big Four taking up Big Law's mantle, especially in the US.

Bar rules continue to prevent non-lawyer ownership of law firms. And the 2002 Sarbanes-Oxley Act, enacted in the wake of the Enron and WorldCom accounting scandals, barred the accounting firms from providing non-auditing services to their audit clients.

Deloitte spent a year figuring out how to work around that first barrier in its tie-up with BAL.

"It's very smart on their part," said James Jones, who directs the Georgetown University centre. "Under practice rules in the US, they can't acquire a law firm, but they can in the UK and other countries."

Representatives from both entities were at pains to emphasise that the global organisation's US arm had no connection to the arrangement.

"They've managed to develop some form of a relationship that everyone has realised is good for their business," Poor said. "It shows that in some ways, you can continue to thread that needle."

Expect to see similar creative approaches employed on practices beyond immigration that cross international borders.

"Some in legal used to say: 'The Big Four are interested in tax and distinct areas.' Well, they're not," said Kent Zimmermann, a consultant with the Zeughauser Group. "Wherever they can find an opening, wherever they can find a workaround, they're all over it."

Promising future destinations for the Big Four include international arbitration, cybersecurity and data privacy, along with certain areas of intellectual property, particularly global registration of patents and trademarks.

But there are signs the Big Four are looking even higher up the food chain. Zimmermann said that one law firm he works with was recently competing with one of the organisations to land a highly sought-after Hong Kong private equity partner.

"I think it's telling that private equity is an area that they're clearly competing in in some international money centres," he said. "The extent to which they take market share in those high-rate areas, that's really going to sting for international firms."

Similar moves are also afoot in London, demonstrated by former Eversheds Sutherland partner Richard Lewis's 2017 move to lead the corporate and commercial practice at KPMG.

"A number of London firms can count on ones and twos the partners and senior lawyers leaving," Ranson said.

Advantages

Ranson believes that within the next five years, "at least one of the Big Four" will boast of its legal wing as a "main stream of service", competing with the top 20 law firms in the world on the basis of both size and revenue. Several factors will ease the accounting giants' path.

"Through their consultancy services in particular, they are very well connected with clients at the board level," he said. "They can take their ideas directly to decision-makers in a way that law firms cannot."

These organisations' mammoth size also allows for economies of scale, and Ranson also said they outpace law firms in their investment in technology to provide services.

Even within the US, there are lanes for these organisations to grow, according to Jones, who argued that the list of activities that can only be performed by lawyers is not especially long. Drafting contracts, conducting due diligence and negotiating M&A are not on it.

"There's a lot of stuff that people like Deloitte and the other Big Four firms and other non-traditional service providers can do without stepping over that line into the unauthorised practice of law," he said. 

And he argued that without the regulatory pressure from the bar, these organisations can be more nimble in how they structure their operations.

"They're pushing the boundaries and trying to get as close to the edge as they possibly can," Jones said. "Sarbanes-Oxley once restricted what they could do. Most people thought they'd put a wooden stake through the heart of the vampire. But that vampire is alive and well."