The "International Will" was described in the Uniform International Wills Act, and is described in detail here
Only 12 countries support an International Will (which in essence means that you can write a Will in any language and it will be accepted by the local courts). Most countries are not included. Even within these countries there is inconsistency, for example, in the US, 23 States are signed up to the International Wills Act, but most are not.
The Act itself, does not provide much useful guidance for preparing a Will and is extremely vague in the text and clauses that it uses.
Our recommendation is that you do not attempt to prepare a Will that will be accepted in multiple countries. We recommend that you prepare a Will for each country in which you hold assets so that for example, you would have a Will for your US assets, a Will for your Canadian assets and a Will for your UK assets. Each Will would be written in accordance to the laws of that country.
However, you cannot use a standard Will service because a standard Will typically revokes (cancels) all previous Wills. Our Expat Will is worded such that it only covers the assets in that country and does not deal with assets held outside of that country. Most importantly, it does not revoke any Will that you already have in place for another country's assets.
The opinions expressed herein by "ExpatLegalWills.com" are designed to provide educational information only and are not intended to, nor do they, offer legal advice.