The legal press is full of internationalisation, firms opening and acquiring new overseas offices, recruiting lateral hires and creating new alliances.

Much advice is given to managers on how to pursue an international strategy, but little advice is given to individual partners tempted to change firms or merge their practice with one of the "internationals".

Having been a lateral hire 10 years ago, I am sometimes asked what is involved in making a lateral move or merger, and, less often, I am tempted to proffer some advice. I preface this by saying that, since my partners are perfect in every way, my advice is only to a small extent based on personal experience. But I have identified some rules to bear in mind when contemplating such a legal marriage.

Some firms feel they want to "go international", others feel they have to. The former will probably be there for the long haul. The latter will probably discover that it makes little difference to their bottom line and, besides, a bunch of foreigners complicates their lives. The lesson here is to go with the ones who want to do it.

However useful as a means of marshalling your thoughts, never believe a business plan, even those which are produced in good faith (i.e. not with a view to persuading recalcitrant partners to vote for the expansion plan).

A firm offering you more than a third of your fee earnings is diluting its equity. Why would they want to do that? Your earning capability is what you bring and what they add, the former rarely becomes clear until the second year and you have no real idea of the latter.

Beware of year three. It is the peak of investment and expectation. "Where is the practice you promised to bring us?" "Where is the clientele you promised to provide me?" In your new relationship, it is the make or break year.

If you are ambitious for power, think twice. Remember you are joining a branch office even in the most geographically diverse firm. Power and decision-making is centralised. Whatever your influence, you will never control a foreign firm from your branch.

Question your motives. If your motive for leaving is dissatisfaction and it is within yourself it will follow you to your new firm. If it is an issue of your relationships with others, remember all partnerships are a continuous process of self-justification, adjustment and negotiation. You will likely find the same characters in the new firm as you had in the old.

The right move can provide a wonderful break from big firm preoccupations and may offer a chance to practice cutting-edge law in a small environment where you will have greater control of your professional life.

The right partnership is a great place to pursue a professional career. If you are not in it, look for it.