Courts deciding whether to permit a leave to remove application are guided by three leading precedents.
Poel v Poel
The first precedent is Poel v Poel  1 WLR 1469 in which a mother applied to take her three-year-old child to New Zealand. Lord Justice Sachs’ ruling has dominated all cases since,
When a marriage breaks up, then a situation normally arises when the child of that marriage, instead of being in the joint custody of both parents, must of necessity become one who is in the custody of a single parent. Once that position has arisen and the custody is working well, this court should not lightly interfere with such reasonable way of life as is selected by that parent to whom custody has been rightly given. Any such interference may, as Winn LJ has pointed out, produce considerable strains which would be unfair not only to the parent whose way of life is interfered with but also to any new marriage of that parent. In that way it might well in due course reflect on the welfare of the child. The way in which the parent who properly has custody of a child may choose in a reasonable manner to order his or her way of life is one of those things which the parent who has not been given custody may well have to bear, even though one has every sympathy with the latter on some of the results.
Note: the use of the word "rightly"; in other words, if you are the non-resident parent you have already been judged unfit to care for your child and half the battle has been lost.
Payne v Payne
The second precedent is provided by the judgement given in Payne v Payne  EWCA Civ 166 by the then President, Elizabeth Butler-Sloss, and Lord Justice Thorpe. A mother had applied to move her child to New Zealand; the lower court rejected her application and she appealed. The father sought to use the recently introduced Human Rights Act, and in particular the Article 8 right to respect for family life, to counter the application. His case was catastrophically hampered by a CAFCASS officer who was ignorant of the law and based her limited understanding on notes made by a colleague at a seminar she herself did not attend.
Thorpe held that since the principle of the child’s welfare always remained paramount, Article 8 could be discounted; he also pointed out that Article 2 of Protocol 4, though not yet ratified by the UK, protected the “right to liberty of movement and freedom to choose his residence” and that the right to family life was thus not the only right to be weighed.
Elizabeth Butler-Sloss derived from Payne the criteria which would henceforth apply in leave to remove cases: “the following considerations should be in the forefront of the mind of a judge trying one of these difficult cases”,
a) The welfare of the child is always paramount, so all aspects of the welfare checklist must be considered, and the child be given the opportunity to express his feelings;
b) There is no presumption created by s.13(1)(b) in favour of the applicant parent;
c) The proposals for relocation must be practical and include measures for ensuring continued adequate contact with the other parent;
d) Consequently, the proposals have to be scrutinised with care and the court needs to be satisfied that there is a genuine motivation for the move and not the intention to bring contact between the child and the other parent to an end;
e) The court must consider the effect upon the applicant parent and the new family of the child of a refusal of leave;
f) The court must consider the effect upon the child of the denial of contact with the other parent and in some cases his wider family;
g) The court must consider the arrangements for ensuring continuing contact between the child and the remaining parent.
These points apply only where the question of residence is not an issue: the court should first consider which parent should be the resident parent, taking into account where the child will live, and any plans the parent has for relocation.
Note: that these criteria do nothing to ensure that contact between the child and the “left behind” parent continues. According to the father’s counsel, Philip Cayford QC, commenting 10 years later, all contact between father and daughter ceased following the mother’s move to New Zealand; clearly the mother had not been committed to preserving contact. Thorpe had been dismissive of the father’s legitimate concerns – “International travel is comparatively cheaper and more competitive than ever before. Equally communication is cheaper and the options more varied”.
Thorpe employed two crucial principles to allow the mother’s application. The first derives from the ideology of the primary carer, i.e. that a child can have only one primary carer on the separation of his parents, and that once custody is awarded to that parent they have almost unlimited rein to do as they choose. Thorpe chose to call this principle “natural emigration”; he held that the court has no right to interfere with a mother’s right to move abroad if she wishes to do so; it would be what he was later to term “an unsustainable restriction on adult liberties”. To frustrate “natural emigration” risked the survival of the new family or blighted its potential for “fulfilment and happiness”. The fact that the ruling would mean a loss of the relationship with the children’s father was inconsequential,
These are the tides of chance and life and in the exercise of its paternalistic jurisdiction it is important that the Court should recognise the force of these movements and not frustrate them unless they are shown to be contrary to the welfare of the child.
Often there will be a price to be paid in welfare terms by the diminution of the children’s contact with their father and his extended family.
Thorpe’s second principle can be termed “detrimental impact”; he ruled speculatively that the mother should be allowed to remove the child from the jurisdiction since to refuse permission would have a “devastating” effect on her “psychological and emotional stability”,
Refusing the primary carer’s reasonable proposals for the relocation of her family life is likely to impact detrimentally on the welfare of her dependent children. Therefore her application to relocate will be granted unless the Court concludes that it is incompatible with the welfare of the children.
In Thorpe’s mind the child is only caused harm – and thus the welfare principle is engaged – through the mother, the primary carer. The father is not the primary carer and thus any diminution in his ability to care is not deemed harmful. In a key speech on relocation  Thorpe clarified,
In the paradigm case the Court weighs the impact on the mother of refusal against the diminution in the father’s contact. This balance is struck in the context of the welfare of the child. Thus the harmful impact on the mother is taken to be harmful to the child: the diminution in contact is a deprivation of the child’s right to relationship with his father.
You might say – not unreasonably – that any harmful impact on the father cannot be harmful to the child if the father is out of the picture, but Thorpe is not consistent and he reverses his principle when the parent wishing to remove is the father. In Re H (Agreed Joint Residence: Mediation)  EWHC 2064 (Fam),  1 FLR 8 a father who had been granted residence (the mother was an alcoholic) proposed to move with his children to Northern Ireland; Thorpe prevented the move and the appeal was dismissed. The judge used the welfare test and took the view that the effect on the mother would be devastating, as would be the knock-on effect of her devastation on the children. Thus detrimental impact is linked to the primary carer only when that parent is the mother.
the great importance of not imposing on primary carers’ restrictions on their freedom to choose their preferred way of family life and their preferred place of residence for two good reasons. The first is that often the notion of such restrictions are simply contrary to good sense and, secondly, because the imposition of restrictions is likely to have an adverse effect on the welfare of the children indirectly through the emotional and psychological disturbance caused to the primary carer by denial of the freedom to exercise reasonable choice.
Thorpe’s appeals to “good sense” and to “likelihood” are hardly compelling arguments. If fathers wish to remain involved, his preferred solution is that they should relocate too, though he regrets that the Court cannot order that,
In such cases the Court has not the power to order the result that would best serve the interests of the child.
We would argue that the Court does indeed have this power which it can exercise by refusing leave to remove.
Re Y 
The precedent in Payne applies principally to cases in which one parent is clearly identifiable as the primary carer; in many cases a residence order will identify her as such. In cases in which care is shared more equitably Mr Justice Hedley’s ruling in Re Y  2 FLR 330 applies. In this case the parents, an American mother and English father, lived in Wales and had an informal post-divorce arrangement of nearly equally shared parenting. The child grew up bilingual with Welsh as his preferred language.
The mother applied to remove the child to the USA; the father countered with an application for shared residence. The mother’s application was refused and the father’s accepted. The case did not fall within the ambit of Payne; the child’s home was equally with both parents; the child’s best interests were served by allowing him to remain in Wales.
I have adjourned this case into open court with, of course, the consent of both parties, for two reasons. First, because this case falls factually outside the ambit of well-settled authorities in this area of the law. It demonstrates, in a way few cases can, quite how, when everything has been said, done and considered the ultimate test remains the welfare of the child, which in the last analysis overbears all other considerations, however powerful and reasonable they may be. Secondly, because this type of case of trans-national marriage is and will continue to become increasingly common, and it seems to me that there should be public awareness of and discussion about the intractable problems that it can raise and the sad consequences that can ensue.
In Re K (Children)  EWCA Civ 793 a Canadian mother applied to take her two young daughters to Canada. The Polish father objected on the grounds that care was shared more-or-less equally. CAFCASS recommended the mother’s application be refused. In the lower court, however, her Honour Judge Bevington granted the application.
The father appealed. The Court of Appeal allowed the father’s appeal: Bevington had rejected the CAFCASS report without sufficient explanation; she had relied on the Butler-Sloss criteria in Payne and not on Hedley in Re Y and had referred only to the mother’s case. Payne provided guidance only and its importance should not be overstated; it should be applied only where there is a clear primary carer. Each case should be decided on its own facts and merits with the child’s welfare always the paramount consideration. Thorpe said,
Where each is providing a more or less equal proportion and one seeks to relocate externally then I am clear that the approach which I suggested in paragraph 40 in Payne v Payne should not be utilised. The judge should rather exercise his discretion and grant or refuse by applying the statutory checklist in section 1(3) of the Children Act 1989.
In Re F (A Child)  EWCA Civ 1364 Lord Justice Munby warned parents against getting too bogged down in whether a case is a Payne case or a Re Y case and that such labels can be unhelpful; it is always the best interests of the child that are paramount.
In 2009 two Spanish parents moved with their 7-year-old child to the UK. The relationship broke down and the mother returned to Spain expecting the child to follow, but the father retained the child in the UK and became the primary carer.
Both parents made shared residence applications and the mother sought leave to remove the child to Spain. Although the child was deemed by Holman J to be habitually resident in the UK Marston J gave the mother leave and made a shared residence order giving the father a week at Easter and 5 in the summer.
The father appealed on the basis that Payne did not apply as he was primary carer and neither did Re K as this was not a shared residence case. The expectation clearly stated in Payne is that the primary carer is the applicant; in Re F, perhaps uniquely, it was the respondent, and the father’s case thus seems valid: the case should have been tried as a transfer of residence. Had that been done, it is likely the mother would not have been given residence and would therefore not have been granted leave to remove. Clearly, and erroneously, Marston treated the mother as the primary carer; he asked himself the wrong questions and thus the child’s best interests were not addressed.
If you are an unmarried father without Parental Responsibility your position is weakened. For example In Re C (Child Abduction) (Unmarried Father: Rights of Custody)  EWHC 2219,  1 FLR 252, FD, Mr Justice Munby (as he then was) considered a case in which the mother of the child had taken him to Ireland. The father sought his return under the Hague Convention.
Because the parents were not married the Court had to consider whether the father had rights of custody within the meaning of the convention despite not having Parental Responsibility under English law. Munby J held that the case was indistinguishable from the decision of the House of Lords in Re J, also reported as C v S  2 All ER 961. Consequently, the father was not to be regarded as having custody rights under the Convention.
At best, the father could argue that he was caring for the child jointly with the mother, a situation considered in C v S. Obviously these responsibilities had ceased by the time the mother took the child to Ireland. The father then raised an alternative argument, that the Court was seized with the issue of custody because his application for a Residence Order had been made by the time the mother left the country, although it had not been served.
Munby noted that the issuing of proceedings in wardship was sufficient to give rise to custody in the Court, e.g. Re J  1 FLR 276 and Re B-M  1 FLR 979. Similarly, the Court was seized of the case for Convention purposes when a judge had exercised a judicial discretion over the conduct of proceedings (even if in fact there was no substantive order, only directions); see Re J  2 FLR 653. However, a mere administrative step without judicial involvement was insufficient (Re H  2 All ER 1). In Re C the father’s claim failed. The Court was not sufficiently seized of the case as to have rights of custody vested in it.
The lesson to be drawn from this, as Munby pointed out, is that unmarried fathers who fear the immediate removal of their children should issue proceedings and apply immediately to the judge for relief in order to ensure that there will be a remedy under the Hague Convention should the child be taken from the jurisdiction. Otherwise, there is a gap in the protection offered between the issuing of proceedings and service.
 Lord Justice Thorpe, Relocation: the search for common principles, speech delivered to the London Metropolitan University, 30 June 2010