How can the court decide whether a handwritten will is valid?  In England and Wales, a will is only valid if it has been signed by two witnesses, and in Scotland by one witness.  So, the first step is to approach the witnesses, whose signatures appear on the purported will, to check if they actually saw the deceased signing the will. 

If there is doubt about the witnesses' evidence, (for example because the witnesses are too closely connected to the person who benefits from  the will), then getting a report by a hand writing expert is the next step.  Hand writing experts vary in competence and experience. The evidence of an experienced, well respected hand writing expert will be taken seriously by the court.  These experts can reach a decisive view as to the validity of the signature on the will by comparing the pressure applied, the slant of the lettering, the particular formation of the letters with other examples of the deceased's writing. 

A handwritten will may be valid if it complies with all the requirements of Section 9 of the Wills Act 1837.  But handwritten wills can lead to more disputes than a will formally drafted by a solicitor because they are more likely to be invalid for want of proper execution.