Maxine abandoned Eric. (spoilers)
That boy deserved nothing but love, appreciation and gratitude for what he did. The fact that the knife was actually his and he lied about it may be unethical in the eyes of the law, but considering his history it was completely understandable that he was so afraid to go back to jail that he was willing to lie on the stand. I find the fact that Maxine couldn't get past this very strange and dissappointing, and also somewhat out of character. She bends the rules so many times for people who mean far less to her, but she couldn't do it for the one person who most depended on her. I fully blame her for Eric running away and I find it one of the most painful story arcs of the series. She really let him down.
I love Maxine's character, but I feel very angry at her for this.
Also, on a side note, possession of a weapon does not necessarily constitute premeditation. He could have simply been carrying it for protection, and that's exactly what he used it for. If he hadn't, Jason Lobdel WOULD have absolutely done harm to the family, and everybody knew it.