Kernrechtsfrage
Whether the cantonal court used the correct comparison dates for revision of the invalidity pension under Art. 17 LPGA.
Extrahierter Entscheid
The court had to compare the medical and factual situation at the 2 June 2004 decision with that at the 4 February 2009 decision, not with the 1994 decision.
Extrahierte Begründung
For a revision, the decisive comparison is between the last material decision that entered into force and the new decision. The cantonal court relied on the wrong baseline decision and therefore applied federal law incorrectly.