Dehler grew up in a Roman Catholic family, but in 1927 he joined the masonic lodge Zur Verbrüderung an der Regnitz in Bamberg.

Dehler was also opposed attempts to reintroduce the death penalty, which the Basic Law had abolished in 1949 for Hitler/Nazi enemies.

In his opposition, Dehler argued not so much against the death penalty itself but in favour of a loyal approach towards the young constitution.

Dehler initially supported Adenauer's western policies - integration into NATO and rapprochement with France - as a means to gain enough international trust and weight to attain German reunification.

Notable points of disagreement were the Saar issue, on which Adenauer cautiously tried to avoid conflicts with France, which tried to keep the region as its protectorate, without giving up German claims, and the Stalin Notes of 1952, which Dehler considered a sincere offer worth exploring further.

Others conceived of it as a party of "national gathering" that should appeal more to the right wing of the political spectrum and integrate it into the democratic system; the chief proponent of the latter strategy was Friedrich Middelhauve of North Rhine-Westphalia.

In this context, Werner Naumann, formerly an aide to the Nazi regime's Propaganda Minister Joseph Goebbels, and other former high-ranking Nazi officials, conspired in an attempt to infiltrate the FDP and gradually turn it into a National Socialist force, especially targeting the North Rhine-Westphalia branch.

They were warmly welcomed by Middelhauve, whose co-operation went so far as to present a German programme, a nationalist manifesto penned by the conspirators at the federal party convention in November 1952.

Dehler, along with Fritz Neumayer and Alfred Onnen, formed an internal fact-finding committee that reproached parts of the North Rhine-Westphalia branch.

The Federal elections of September 1953 resulted in large gains for CDU/CSU, while its coalition partners sustained slight losses.

However, because of the Minister of Justice's increasing differences with the Chancellor and because of "a serious breach of confidentiality" in the context of the Naumann affair, Dehler was replaced by Fritz Neumayer.

Immediately after his departure from government, Dehler was elected chairman of FDP's parliamentary group and of the federal party, replacing Hermann Schäfer and Vice-Chancellor Franz Blücher, respectively.

The reasoning behind this move was that the FDP deputies blamed their party's losses in the election on a lack of distinctive profile and now choosing an opponent of Adenauer as their leader.

A major issue for Dehler was the replacing Bavaria's system of denominational elementary schools, which had been restored after the fall of the Nazi regime, with interdenominational institutions.

After the CDU/CSU's triumphal victory at the Federal elections of 1957, the coalition fell apart when the BHE and the Bavaria Party withdrew their ministers.

Arnold had governed as head of a CDU-FDP coalition but now the FDP switched their allegiance to elect the Social Democrat Fritz Steinhoff.

However, as in its Bavarian counterpart, success was short-lived, as CDU gained an absolute majority in the 1958 state elections and returned to government with Franz Meyers.

It was in 1956 as well that Dehler made his decisive move against Adenauer: On 23 September 1956, just a year before the next federal elections, the FDP parliamentary group in the Bundestag decided to leave the coalition with CDU/CSU.

He was an unyielding opponent of attempts to exempt Nazi crimes from the statute of limitations by citing basic legal principles.