This blog isn't really my opinion on Herbert Smith – I'm keeping my powder dry for a little longer on that one – but this week's effective break-up of the City firm's merger hopes and European alliance does illustrate a factor that has been hugely on display throughout this year. Amid a hectic 10 months in which we have seen a stream of international tie-ups across the globe, many of the far-reaching decisions taken by law firms have been substantively shaped by a single consideration: who gets to be the boss afterwards.

Ashurst and Blake Dawson; the continued expansion of the Norton Rose Group; Mallesons/King & Wood; and the break-up of Herbert Smith's alliance with Gleiss Lutz and Stibbe – what they all have in common is that these events happened partly because individual partnerships had ambitions of remaining a dominant party in a global consolidation play.

As has been said for years, a merger between Ashurst and Latham & Watkins would have been a potent combination had it gone ahead as discussed in 2000, but it wasn't to be. Sure, a lot of City lawyers found Latham circa 2000 a bit too happy clappy (and with an incomprehensible comp system to boot), but a major factor in why the deal didn't close was because Ashurst would have been the junior partner.

Now, I can certainly see a solid case for the Blake Dawson union (the critical drubbing it's taken from rivals looks excessive, especially since Norton Rose/Deacons was originally panned but was later acknowledged to be working well). But what you can say about the Anglo-Australian deal is that it partly happened because Ashurst wanted to remain the dominant party as it goes properly global, something that would have been harder to do if it went for the more obvious short-term step of a US merger. The firm still wants to do a deal in the US – but believes it will have more leverage having built a top-flight Asia-Pacific practice several years down the line.

There's a similar logic at play with the Norton Rose Group: if we surround the Americans with an awesome enough empire we can get better terms when the time comes. Likewise, King & Wood and Mallesons both get a respectable shot at going global without having to submit to the demands of a more powerful US or UK law firm. In the case of Herbert Smith's recent setback, Gleiss and Stibbe obviously never wanted to give up their independence. First it was because Herbert Smith was more profitable than Gleiss, then not profitable enough. In the end, that's details. Gleiss just didn't want to do it – they didn't want to be taken over. (Herbert Smith is surely right to pull out of the alliance and probably should have done it years ago; a union partly based on how it plays in M&A league tables is not going to last forever).

In many cases the outcomes of these tie-ups and splits look like reasonable decisions; King & Wood Mallesons is a hard one to call and a lot could go wrong but the potential upside is off the chart. But this doesn't change the underlying fact that lots of deals in the legal industry that should get done in business terms don't because everyone wants to be top dog.

It's a particularly thorny problem when trying to put together transatlantic deals. US and UK law firms are the two dominant powers that define the global legal market. Frankly, neither breed of institutional alpha dog wants to roll over. That's the single biggest obstacle that has blocked the majority of US/UK deals over the last 15 years. Law firms call it culture, but that's what they mean.

That raises some awkward questions for Norton Rose and Ashurst. American lawyers are even prouder than their British counterparts. You could even make a case that the two firms' empire-building will make it harder to get a good deal stateside as the US suitors they are interested in will be wary of being swallowed by a larger firm. That's not just supposition – one US firm typically regarded as very high on Norton Rose's wish-list has already taken to claiming that it is less likely to consider a merger with the City firm because of Norton Rose's series of mergers. Who wants to be a cog in someone else's machine?

A final point: why do law firms pursue 'mergers of equals' deals so obsessively? It's like chasing leprechauns – these mergers are a nightmare to find and worse to actually make deliver. But they are still pursued because they hold the seductive possibility of transformation without anyone having to give ground. If you find that pot of gold, great, but it's very, very rare.

It's a hard, hard thing to accept giving up your dominant status – or perhaps worse your sense of freedom, however illusory that may be. But in the years to come, it would be wise for more large law firms to consider just such a step. At least if they want a shot at the big time.