A good question, asked a surprising number of times. The short answer is “yes,...but....”. There is a presumption of testamentary freedom under English law in making your will, ie you can leave your assets to whomever you please, (unlike a country such as France, where there are forced inheritance rules). However, legislation does exist to protect those who it is felt deserve special protection.
The Inheritance (Provision for Family and Dependants) Act 1975 (“the Act”) defines certain categories of people who may make an application to the court (within a strict timescale) for financial provision.
These are obvious candidates such as spouse, co-habitee, children or someone who was being maintained by the deceased immediately before death. The claimant must prove that reasonable provision has not been made in the will and a spouse commands a more favourable definition of financial provision than other claimants. Generally speaking, able bodied adult children, who are capable of maintaining themselves are not treated very favourably by the courts.
If you are thinking of disinheriting someone who is covered by the Act, then you should think about leaving a written statement giving your resons for omitting someone who might have expected to have been provided for in the will. If those reasons are good, true and accurate, the court will take them into account.