Why does it say "Hoy"?
Malbim: This calls out [to sinners]. It is connected to verse 3 - what will you do on the day of Pekudah?!
What are "[ha'Chokekim] Chokekei Aven"?
Rashi: They are evil, forged documents.
Radak: The Neveilah discusses judges and their scribes. The judges tilt the verdict, and tell their scribes to write the verdict, so they will last. Ha'Chokekim are the scribes; and Mechatvim are the judges. This is Po'el Yotzei li'Shelishi (the subject makes another act on a third party); they command the scribes to write writings of oppression.
Malbim: The judges laid protocols of sin.
What are "Mechatvim"?
Rashi: This is Arabic; in Hebrew it is Michtavim (writings).
Malbim: Commoners wrote writings of oppression.