just my 2 cents

1. Dr. Tao did nothing wrong

2. The police or security should have never involved in this case becasue it is customer servies issues, not safty issue. They should have rejected stepping in the plane. The more recent information indicate: the security guard won't allowed in the plane, only limited in the certain areas of airport.

3. Certainly there is a race issue in this case. What is the random chance to pick up Dr. Dao and his wife in the random chance by computer? not mention, other 2, also reported are asian (not sure for that part)

4. The UA manager/staff thought that they know the overbooking law and rules, and they can do whatever they want. actually they really don't know the law. In this case, even not a overbooking case. Even, overbooked, you still could not order or removed the payiing, boarded, sitting in his seat customer,  who does not threaten to anyone, even the police.

5. This case became very interesting, because of Dr. Dao's background, probably related to the CEO of UA the first 2 statements, which dig the hole deeper

6. Dr. Dao is the one who was actually fighting for all customers, although happened that he needs to see his patients next day.

7. UA and the security guards broken the laws, which require to give customers written statement (certainly they did not) why they were chosen if it is in a overbook case, which is not in this case

8. According to the latest information, the main polite did not call the security guard, who came on the plane. The polite is like the capitain who is supposed in charge.

9. The injury happened in the plane, even the UA staff did not directly involving in dragging, but they are liable.

10. We still do not know the more details of case