Lawyers representing a civil servant accused of distributing Japanese Communist Party material before the House of Representatives election in November demanded Tuesday that the case be dismissed, saying his freedom of speech is being violated.

The defense team of Social Insurance Agency worker Akio Horikoshi, 50, also said at the opening session of the trial that the unrelenting probe carried out by public security investigators at the Metropolitan Police Department was illegal and violated his human rights.

They argued that Horikoshi's conduct was legal and that he was exercising a constitutionally protected right to freedom of speech.

Horikoshi was indicted in March for allegedly distributing a special election edition of the JCP newspaper, Shimbun Akahata, in his free time to passersby on the street and in mailboxes prior to the election.

Prosecutors claim that his conduct violates the National Public Service Law, which bans public servants from engaging in political activities.

But Horikoshi told the court that the law is unconstitutional as it violates his right to freedom of speech.

"Why should I be deprived of freedom of expression, guaranteed under the Constitution, just because I am a civil servant?"

At Tuesday's session, presiding Judge Yujiro Nakatani agreed to a request by defense lawyers for prosecutors to disclose their evidence against Horikoshi, mainly video footage of the defendant distributing flyers, so that they could better prepare their case.