County Assembly Speaker Harub Ebrahim Khatri has accused Devolution PS Nelson Marwa of ruining him financially and socially.
Mr Ebrahim said Marwa tainted his reputation by linking him to narcotics and illegal gun possession.
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The two are old rivals from Mr Marwa's days as Regional Coordinator for Coast.
When the altercation between them began last year, Ebrahim held no public office.
Marwa has battled a defamation suit filed by Ebrahim for long and even attempted to have an out-of-court settlement.
Early this year, Marwa lost a battle in the Court of Appeal when it ruled that he must personally answer to the charge.
Marwa and the Attorney General had expunged the latter's name from the suit, arguing that as a Government official he could not be sued for remarks made in the course of his official duties.
Remarks by employees
However, the Court of Appeal ruled that the Government could not be held liable for defamatory remarks made by its employees.
Ebrahim, who testified before Justice Dorcas Chepkwony, said besides ruining his business opportunities and tarnishing his name, Marwa's claims had made it difficult for him to court and marry any woman.
Additionally, the Speaker said Marwa put his life in jeopardy by linking him to drugs and illegal guns.
"I'm young and not married, and I have lost two lovers after they read bad things about me on the internet," Harub claimed.
Hearing continues on January 14.