The first civil partnerships were formed on 21 December 2005, after the Civil Partnerships Act 2004 came into effect on 5 December 2005. Same-sex marriages contracted abroad, however, have been recognised as valid civil partnerships from 5 December 2005. Whilst the legal formalities may differ from those of marriage, the practicalities make them almost identical, including the granting of the full range of paternity and child care rights enjoyed by married couples.

A civil partnership can be terminated only by death, legal dissolution or annulment and dissolution is allowed, as in marriage, only on the grounds of irretrievable breakdown. One difference between civil partnerships and marriage is that adultery is not a ground for irretrievable breakdown in the former, but is in the latter. On the breakdown of a civil partnership, the normal claims for financial relief – such as division of assets and maintenance payments – apply as in a marriage and with the first breakups of civil partnerships already taking place, it is clear that the courts are taking the same approach to dissolutions of civil partnerships as they do in the breakdowns of marriages.

Civil partners have the equivalent rights of a spouse on the death of their civil partner, so the same sort of thinking needs to be applied towards making a will and Inheritance Tax planning as should be done by married couples. A civil partnership, like a marriage, invalidates an earlier will.

More recently, the Government has announced that same-sex couples are to be allowed to hold civil partnership ceremonies in churches and other places of worship in England and Wales.

In 2012 the first 'high net worth' dissolution of a civil partnership occured. The decision of the court confirmed that the same principles on the sharing of assets apply when a civil partnership ends as apply when a marriage ends.

In July 2013, the Marriage (Same Sex Couples) Act 2013 was passed into law. This effectively puts same-sex marriages on the same footing as heterosexual marriages and deals with some of the anomalies that result.

Among other important legal issues dealt with by the Act are:

• Same-sex marriages solemnised in foreign jurisdictions before the passage of the Act will be recognised as marriages in England and Wales;

• It does not change the effect of any ‘private instrument’ made before it comes into force. So, for example, the definition of ‘spouse’ in an existing Trust providing for children and spouses would not include same-sex spouses; and

• It does not extend the common-law presumption that a child born to a married woman is also the child of her spouse to the circumstance in which the spouse is also female.

It also provides that civil partnerships may be turned into same-sex marriages. However a court ruling in 2017 confirmed that heterosexual couples cannot formalise the relationship using a civil partnership.

One aspect of non-equivalence that should be mentioned is that where a ‘private instrument’ (such as a trust document) was created before the Act was passed, the term ‘spouse’ will not include a same-sex spouse. However, it has been confirmed that when a civil partnership is turned into a marriage, the wills of the civil partners continue to be valid.

In 2017, a ruling by the Supreme Court confirmed that  same-sex spouses and civil partners must receive the same rights in respect of their occupational pension entitlements for dependants as do heterosexual spouses. Prior rulings limited the entitlement insofar as those rights relate to pension rights accrued before the passing of the Civil Partnerships Act.

When a heterosexual couple lost their court battle to have a heterosexual civil partnership, the Supreme Court found this was a breach of their human rights and the Secretary of State was ordered to bring regulations into effect by the end of 2019 to allow heterosexual couples to become civil partners,