1- A made a contract for a house with B. Subsequently, B sued A for breach of contract. A raised the defense that the contract was not binding because it was not sealed. Is that a valid defense?

2- Dozier and his wife, daughter and grandson live in the house Dozier owned. At the request of the daughter and grandson, Paschall made some improvement on the house. Dozier did not authorize these, but he knew that the improvements were being made and did not object. Paschall sued Dozier for the reasonable value of the improvements, but Dozier argued he had not made any contracts for such improvements.

3- When Harriet went away for the summer, Landry painted her house. He had a contract to paint a neighbor's house but painted Harriet's hour by mistake. When Harriet returned from vacation, Landry billed her for 3,100 and she refused to pay. Landry claimed that she had a quasi-contractual liability for that amount.

4- When a college student complained about a particular course, the vice president of the college asked the teacher to prepared a detailed report about the course. The teacher did and then demanded additional compensation for the time spent in preparing the report. He claimed that the college was liable to provide compensation on an implied contract.

5- Smith made a contract to sell automatic rifles to a foreign country. Because the sale of such weapons to that country was illegal under an act of Congress, Smith was prosecuted by the U.S. government for making the contract. He raised the defense that because the contract was illegal, it was void and there is no binding obligation when a contract is void; therefore, no contract for which he could be prosecuted existed. Was he correct?