Answer:
he lacked the mental capacity to enter into the contract
Step-by-step explanation:
In contract law, someone who lacks capacity to enter into a contract can be said to be someone who is not mentally sound, and hence, such incapacity would render whatever contract such person enters voidable. Being intoxicated is one of the factors that can render one incapable mentally, and as such cannot legally enter into a contract. If Sven wants to void the contract based on his intoxication, he will have to prove that his mental capacity to enter into the contract was impaired by the intoxication. Only then can the contract be voidable.