Some I have purchased from the GRO (Britain), Scotland, Australia, New Zealand, Canada, Ireland, Zimbabwe and also the USA.
Yes we own the certificate but even our 'own' birth, marriage certificates are legal documents and owned by the government hence copyright.
I am certainly not going to write to each of these countries either by email or letter to see if they will let me use the image (Zimbabwe I've been waiting 28 months already just to find and locate another certificate). 100+ letters etc. It would take a long drawn out process to find out yes/no.
Again 1000+ parish documents from various countries. 550+ newspaper clippings most of which are purely one line eg "Mr Smith of Apple Cottage age 64 died on the 4th inst."
Personally all the work involved would take months and possibly years.
Many kind thanks Jillaine Smith.