Legal analysis: if the parties conclude a contract in the form of a contract, the contract is established when both parties sign or seal it. If no guarantee contract is signed, or the guarantor does not sign a loan contract, the guarantor does not need to bear the responsibility. When the guarantee is a general guarantee, the guarantor has the right of defense, that is, the guarantor has the right to refuse the creditor's repayment request before the creditor applies to enforce the debtor's property or fails to enforce the security interest. Co-guarantors have no such right.

Legal basis: Article 38 of the Measures for the Supervision and Administration of Credit Card Business of Commercial Banks, the issuing bank shall publicly and clearly inform the applicant of the application materials and basic requirements. The application materials must be signed by the applicant himself, and the card shall not be issued without the customer's knowledge or against the customer's wishes.

The application materials for the supplementary card of the credit card accepted by the issuing bank must be confirmed by the main cardholder through personal signature, customer service telephone recording, electronic signature or a way recognized by both the cardholder and the issuing bank.

People's Republic of China (PRC) Civil Code

Article 682 A suretyship contract is an accessory contract to the principal creditor's rights and debts contract. If the principal creditor's rights and debts contract is invalid, the guarantee contract is invalid, unless otherwise stipulated by law.

Article 685 A suretyship contract may be a separate written contract or a suretyship clause in the principal creditor's rights and debts contract.

The forms of suretyship include general suretyship and joint liability suretyship.

If the parties have not agreed on the way of guarantee or the agreement is unclear in the guarantee contract, they shall bear the guarantee liability according to the general guarantee.

Article 196 of the Criminal Law of People's Republic of China (PRC) commits credit card fraud under any of the following circumstances. If the amount is relatively large, it shall be sentenced to fixed-term imprisonment of not more than five years or criminal detention, and shall also be fined not less than 20,000 yuan but not more than 200,000 yuan; If the amount is huge or there are other serious circumstances, he shall be sentenced to fixed-term imprisonment of not less than five years but not more than ten years, and shall also be fined not less than 50,000 yuan but not more than 500,000 yuan; If the amount is especially huge or there are other especially serious circumstances, he shall be sentenced to fixed-term imprisonment of not less than 10 years or life imprisonment, and shall also be fined not less than 50,000 yuan but not more than 500,000 yuan or confiscated property:

(a) using a forged credit card, or using a credit card fraudulently obtained with a false identity certificate;

(2) Using an invalid credit card;

(3) Fraudulent use of another person's credit card;

(4) malicious overdraft.

The term "malicious overdraft" as mentioned in the preceding paragraph refers to the behavior that the cardholder overdraws beyond the prescribed limit or time limit for the purpose of illegal possession, and refuses to return it after being urged by the issuing bank.

Whoever steals a credit card and uses it shall be convicted and punished in accordance with the provisions of Article 264 of this Law.