How do I contest a will
You will need evidence in support of your claim.
If you are arguing that the testator did not have sufficient mental capacity to make a will, it will be necessary to obtain their medical records and perhaps a report from an expert witness such as a psychiatrist to support this.
In a case of undue influence, strong independent witness evidence of coercion will be crucial to your claim. Undue influence can take many forms ranging from threats or pressure to physical violence. It is not unlawful to put pressure on a testator, but pressure to such an extent that it overbears the testator's own wishes may be considered unlawful. Each case is different and will be judged on its individual facts.
In a claim for want of knowledge and approval, evidence that the testator probably did not understand the effect of the will they made or the extent of the property they were disposing of will be necessary, and these claims are often run alongside claims for a lack of testamentary capacity.
Gaining access to the files of the deceased's solicitor may also prove useful as they should have kept notes concerning their client's well being when there is any doubt about capacity.
Access Legal can help you obtain a copy of the file from the solicitor that drafted the will is important as this will contain useful evidence as to the circumstances in which the will was prepared, who was present, and what instructions were given.