The document discusses the doctrine of constructive notice as it relates to companies. It notes that a company's memorandum of association and articles of association, which are filed with the registrar of companies, become public documents. It is therefore the duty of anyone dealing with a company to inspect these documents first before entering into dealings with the company. This doctrine provides protection to companies against outsiders by assuming the outsiders have read and understood the memorandum and articles of association. Two case examples are provided that demonstrate how this doctrine was applied when a mortgage deed was invalid due to missing signatures as outlined in the articles of association.