Ephraim is oppressed and broken in judgment, because he willingly walked after the commandment.
Ephraim is oppressed and broken in judgment - namely, 'crushed' in the "judgment" of God on him (Hosea 5:1).
Because he willingly walked after the commandment - he willfully followed Jeroboam's commandment to worship the calves. (Thus Jehu walked after "the sins of Jeroboam, which made Israel to sin," 2 Kings 10:28-33. "It is too much for you to go up to Jerusalem; behold thy gods, O lsrael, which brought you out of the land of Egypt; and Jeroboam ordained a feast unto ... Israel.") Compare Micah 6:16, "The statutes of Omri are kept, and all the works of the house of Ahab, and ye walk in their counsels" - namely, idolatrous statutes. "We ought to obey God rather than men" (Acts 5:29). Jerome reads 'filthiness' [tsow, for tsaaw (H6673)]. The Septuagint gives the sense, not the literal translation, after vanities.'