Over the next couple of years Iwan Katz's relationship with the party nevertheless deteriorated further. His outspoken approach no doubt reminded Walter Ulbricht and other party stalwarts of the same generation as the leader why Katz had been excluded from the party in 1926. He was openly critical of the twelve month Soviet blockade of Berlin launched in June 1948, sharing his opinion robustly with fellow delegates at a regional party conference at Zehlendorf at the end of the year, also taking the opportunity to launch an attack on the government's latest "two year plan". By this time, as a result of his newly rediscovered appetite for opposition, Katz was "under party investigation". On 21 December 1948 the man who had been dismissed from public office by the Hitler government in March 1933 was dismissed from office for a second time, this time by the Ulbricht government, a new kind of one party dictatorship. The irony is not lost on commentators. Approximately eleven weeks later, on 14 March 1949, Iwan Katz resigned his party membership. Two months after that, on 12 May 1949, he re-joined the SPD.