法律問題.....熟悉法律的人請進.....thx

成年人一個, 無精神病或弱智, 合約為何無效? 對方沒有責任証明你有能力支付費用才簽約的

generally, contract made between parties under free will will be enforcable. whether one has the financial resources to do so is irrelevent.

the contract may however be void if specific event occured, which includes but is not limited to:
misrepresentation (i.e. things said by the sales and relied on are untrue)
duress (i.e. use of threat)
fraud (i.e. deliberately deceiving another)
illegality (i.e. the contract is for illegal purpose)
incapacity (i.e. the person is insane/mentally unsound)

It depends.

Even the person is an adult and competent in signing the contract, if there is anything that beyond the person's control, such as the merchant intentionally commit fraud or misrepresent. It will be a no.

年齡超過18

已是法定成年人

要為自己所做的事情全部負責