(1) Article 14 of the Appraisal Standard for Human Minor Injuries (Trial): "The length of a single facial soft tissue wound is 3. 5 cm (3 cm for children), or the cumulative length of the wound is 5 cm (4 cm for children) or the maxillofacial penetrating injury. "
(2) Article 15: "There are obvious scars after facial injury, with a single length of 3 cm or a cumulative length of 4 cm; A single area of 2 square centimeters or a cumulative area of 3 square centimeters; The pigment affecting the face changes by 6 square centimeters. "
(3) Article 16: "Facial nerve injury causes partial facial muscle paralysis, which affects face and function."
I. Event analysis
1, "By the way, is scratching your face a minor injury?" In fact, you can't "ask by the way" this question, because this is the key to answering your above question:
(1) If it constitutes a minor injury, and Party A has filed a criminal private prosecution, or the procuratorate has filed a public prosecution against Party B, there is a "defense lawyer";
(2) If it does not constitute a minor injury: there is no need to bear criminal responsibility at all, so there is no criminal action, only a civil action, and there is no so-called "defense lawyer" in the civil action, only an attorney.
(3) Whether a scratch on the face can constitute a minor injury depends on the specific injury. According to the "Identification Standard for Human Minor Injuries (Trial)", it depends on the length of the wound.
Minor injury or not: only the forensic expert's conclusion shall prevail, and the suggestions here are for reference only.
2. Nature of the incident: fighting with each other.
3. If it constitutes a minor injury, you can report it to the public security for investigation. After the investigation, minor injuries can be prosecuted or prosecuted. When prosecuting, if B can actively compensate, there is a great possibility of probation; In private prosecution, if B actively compensates and A shows understanding, criminal responsibility can no longer be investigated and only civil compensation can be made.
Second, your question:
1, "Now my question is: Is it legally valid for classmate A to ask classmate B to compensate for medical expenses?" Of course, if there is a loss in fighting, whoever causes the loss will pay for it. A's glasses were broken by B, and B has the responsibility to compensate;
Similarly, B has the right to claim compensation from A for the losses caused by A in the fight.
2. "Now, suppose you are the defense lawyer of classmate A and try your best to help classmate A meet the claim for compensation. What will you take out?" ：
(1) Only if it constitutes a minor injury can there be a defense lawyer. Suppose it constitutes a minor injury.
(2) Article 234 of the Criminal Law (minor injury is intentional injury), Article 170- 173 of the Criminal Procedure Law (criminal private prosecution), Articles 77 to 78 (incidental civil action).
(3) But even if it constitutes minor injuries, A is the plaintiff (in private prosecution, A can only be the victim instead of the plaintiff), and the invited lawyer is not a "defense lawyer" but only an attorney; The lawyer hired by defendant B is a defense lawyer.
(4) This 50 points is too little, and specific laws are needed, hehe.
3. "Suppose you are the defense lawyer of classmate B, how can you refuse this request?" ：
(1) As the defendant, Party B can hire a defense lawyer, but the defense lawyer is only responsible for proving that Party B is innocent and guilty.
(2)B's lawyer can prove that A is at fault for causing losses from the causes of the fight between the two sides and the fault of A's behavior, thus reducing B's liability for compensation.
4. "Finally, suppose that the loss of glasses of students A and B is equivalent to offset.";
(1) In fact, if A's injury does not constitute a minor injury, it is only a simple public security case, and both parties can negotiate or ask the teacher to mediate compensation to solve the problem. There is no need to make it so complicated: according to the fault of both parties, each party can compensate the other party and can support it. If the glasses of A and B have the same price, they will not compensate each other for glasses, and B will only compensate A for medical expenses and transportation expenses.
(2) If negotiation fails and the teacher fails to mediate, it is suggested to report to the public security for settlement.