What is forum shopping?
The phrase “forum shopping” is widely used in the media in relation to divorce.  It describes the choosing of a country in which to raise proceedings which favour your situation best. It supposes that couples have a real choice as to under which set of laws they succumb to.  Is this really true? 
In simplified terms, an action for divorce (or dissolution of civil partnership) can be raised in any country in which one or both parties are habitually resident or domiciled.  The place of marriage has no bearing on the choice of law of divorce.  The issue of forum shopping therefore only arises where the parties to a marriage are living in different countries at the time of raising divorce proceedings.  With the increase in international travel and free movement within Europe, more and more married couples have connections to more than one country and therefore it is increasingly common to have disputes over which country should make rulings on the divorce. 
Why forum shop at all?
There may be many reasons why a party would choose to raise proceedings in one country rather than another.  For example, it may be where they live so access to the court and to local legal representation may be easier for them.  Or the rules on financial provision or the division of assets may favour them in one country more than another.  For example, the party with the greater wealth, and therefore more at stake, is likely to want to avoid proceedings being raised in England where the reputation is for generous settlements to the poorer spouse and the granting of ongoing financial support. 
The specific rules of jurisdiction
The Jurisdiction within the EU
The rules in relation to forum shopping differ depending on whether the dispute is between two international countries or two countries within the UK. The rules within Europe can be found within Council Regulation (EC) No 2201/2003 of 27 November of 2003 (known as Brussels II bis). 
Where parties live in different countries within the EU, it is a “race to the courts” where the first party to raise their divorce application seises jurisdiction in that country and once a country has been seised of jurisdiction then it cannot be interfered with.  So, where parties have lived together in Scotland during their marriage but after separation one of them goes on to live in Germany and raises an action there, then the German courts have priority to hear the divorce, even if the other party subsequently raises an action in Scotland.
Jurisdiction intra UK
The rules in relation to the UK are contained within the Domicile and Matrimonial Proceedings Act 1973 and the Brussels II bis race to the court situation doesn’t apply.  Where a dispute arises between two countries within the UK (i.e. between Scotland and England, for example) it is not the country where an action was raised first who has priority, but the country in which the couple last resided together as husband and wife, and hence the country with which the marriage had the closest connection.  So, if parties have last lived together in Scotland and one of them moves to England and raises an action there, the other is entitled to raise a second action in Scotland and the English Court must stay the proceedings (put the action on hold) until the action in Scotland has come to an end.
Maintenance obligations
Maintenance obligations are governed by a different set of rules under Council Regulation (EC) No 4 (known as “the Maintenance Regulation”) which applies to spousal and child maintenance. 
There are four alternative grounds of jurisdiction: 

habitual residence of the defender;

habitual residence of the pursuer;

the court which has jurisdiction re status and where maintenance is ancillary to these proceedings (but not if jurisdiction is based solely on domicile of one of the parties);

the court which has jurisdiction re parental responsibility and where maintenance is ancillary to those proceedings (but not if jurisdiction is based solely on domicile of one of the parties).

The Maintenance Regulation is similar to Brussels II bis in that the court seised first takes precedence and the mandatory stay procedure of the second court applies. 
Within the UK
The Maintenance Regulation can be applied within the different parts of the UK as well as within Europe, which is a significant difference between it and the Brussels II bis application.  This means that there is a race to the court under the Maintenance Regulation even between jurisdictions within the UK and that where a client has a maintenance claim and could possibly forum shop within the UK, immediate consideration must be given to where would be most advantageous for them so that that jurisdiction can be seised first.
This is a big enough change for family lawyers.  However, the effects of this could extend even further, to have an impact on divorce actions and may conflict with the provisions of the Domicile and Matrimonial Proceedings Act 1973.  This is because an action for spousal maintenance could be either a standalone action or ancillary to a divorce action and it is arguable that claims for a capital sum as well as aliment or periodical allowance may be deemed to constitute maintenance.  So, if parties have lived together throughout their marriage in Scotland then the wife moves to England after separation and raises an action of divorce seeking maintenance there, that court has preference to deal with the action under the Maintenance Regulation even if the husband raises a second action in Scotland seeking a stay of the English action and relying on the provisions of the 1973 Act whereby the court with the closest connection to the marriage should hear the divorce. 
What could the husband have done to prevent the English courts being seised?  He would have had to seise the Scottish courts in relation to maintenance first but if he didn’t have any claim for maintenance against his wife then he may be powerless to do anything.  This could be the case even if the husband raised a divorce action first in Scotland: it wouldn’t prevent the wife raising a standalone action for maintenance in England.
There has been a recent attempt to defeat the provisions of the Maintenance Regulation where a civil partner raised an action in Scotland seeking a maintenance payment from herself in favour of her civil partner in an attempt to seise the Scottish courts first and prevent her civil partner from raising an action in England for maintenance and opening up the more generous doors of the English courts.  This action has been challenged and it remains to be seen whether the Court allows what could be construed by some as a blatant misuse of the Regulation in the ultimate forum shopping exercise.
Conclusion
Brussels II bis and the Maintenance Regulation differ in their applications but both allow forum shopping to an extent.  It is important to consider in which jurisdiction you are most likely to succeed with your claim and seise the jurisdiction of that court quickly in accordance with the correct rules.