This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
Undue influence has, on the other hand, been classed as "a species of fraud."1 So it has been said to be not fraud, but like fraud.2 The type of fraud referred to is, of course, constructive fraud and not actual fraud. It must be admitted that while certain types of constructive fraud can be distinguished clearly from undue influence, there are other forms of constructive fraud which blend into undue influence, and which render the division between the two an arbitrary one, made chiefly for convenience in discussion, and not controlled by principle.