Some of this seems conflicting, witnesses are somewhat vague about the physical confrontation itself, other than the White 17 year old pushing, touching the Black kid to the knife stabbing, which ended the physical confrontation, which was just between those two.   How hard the push was, how long the fight lasted, how many blows were exchanged, etc.   Seems different for different witnesses, supposedly the video is grainy, not real clear, what is more, over a year has passed, so memory is affected. 

 The law and the media seems to have conflicting views, reports, they said it was illegal to have knifes on school ground, period, before.  Yesterday, again, what i heard from the news, an officer said a blade under a certain length is legal, but again, a 17 year old is not a 21 year old, who legalistically, can drink alcohol, own guns, vote, etc, all age based privileges, which can be taken away if a person abuses them.

Texas law does not have a single "Stand Your Ground" statute, but it explicitly removes the legal duty to retreat when defending yourself. Under Texas Penal Code § 9.31, you can use force—including deadly force—if you reasonably believe it is immediately necessary to protect against unlawful force, imminent death, or serious bodily injury. [1, 2]

Key Conditions to Qualify

For the "no duty to retreat" and self-defense provisions to protect you, you must meet three specific conditions