I constructively know something if it is something that I could reasonably be expected to know of.If a contractor that I hired dug that hole in my driveway then I will be deemed to have constructive knowledge of the hole even though I may not have actual knowledge of it. My obligation in regards to that hole may be the same as if I actually knew of its existence.
If a puddle of water remains on the shopping center floor for hours the proprietor may have constructive awareness of that. If there is no evidence as to how long the puddle had been on the floor then there is no evidence of the owner constructively knowing that. Therefore there is no constructive knowledge in that instance. The issue of whether there is constructive knowing is frequently an issue that is submitted to the jury for determination.
If a manufacturer has reason to believe that young children are going to have access to their potentially dangerous product then they have a duty to warn of such danger. That is they have constructive knowledge of the danger. Based on that understanding they may also have a duty to modify their product to make it safe for all users.
For more information on constructive knowledge and other related personal injury issues see the other pages on this site.
For more information about constructive knowledge see the pages on Wikipedia.