The due diligence conducted by the buyer is essential in the discussion between buyer and seller about the warranties to be issued by the seller and their scope. The basic principle under Dutch law is that the seller's duty of disclosure takes precedence over the buyer's duty to investigate.
That said, the buyer should not just blindly rely on the seller and does bear responsibility himself and some active research may be required of him.
Especially in business acquisitions, the buyer may be required to conduct his own research into the company to be purchased. How far this duty of investigation extends depends on the object of sale and the professionalism of the buyer.
The more professional the buyer is, the more research may be required of him. The above is important in the context of warranties to be issued by the seller.
The seller is usually willing to provide extended warranties, with the parties then agreeing that the buyer cannot claim under those warranties if and to the extent that the buyer knew or should have known of any breach of a warranty based on its own due diligence.
This is also known as "disclosure." Guarantees do not apply to the extent that the information to which the issued guarantee relates was "fairly disclosed" by the seller during due diligence.
In short, if the buyer should have known of a breach of warranty based on its own due diligence, it cannot later appeal to the seller for breach of warranty.
After all, the buyer knew this or should have known this and so it comes at his own expense and risk. Buyer and seller usually argue about what exactly should be meant by "fairly disclosed" then.
Typically, sellers want everything that has been in the data room for their perusal to be considered disclosed. In practice, this is accepted by buyers. The buyer, on the other hand, wants to have it included in the purchase agreement that the information in the data room has been disclosed by the seller in such a way that a reasonably experienced buyer and/or his advisors, based on a "first reading" of that information, knew or should have known about the relevance of that information and the possible impact on the warranties to be issued.
To clarify, the buyer wants to prevent the seller, in the event of a breach of a warranty, from arguing to the buyer that the buyer could have known about it based on due diligence by virtue of, for example, a cross-reference in the footnote of a document in the dataroom to another document not in the dataroom.
Thus, the document disclosed by the seller in the dataroom then does not mention that information, but the reference in that particular disclosed document to another document, for example at the bottom of the page in a footnote, could then entail that the buyer should have inquired further and requested those documents as well.
This is a hopeless task for the buyer, which is why the buyer wishes to delineate his duty to investigate as described above.