His intention to take legal action was communicated to the council's chief executive Richard King via email on Monday night.
Last week, the Southland Express reported Cr Ludlow had resigned from the position because he was overcommitted.
It has since been revealed all but one councillor had signed a requisition seeking his removal from the role. Mr Shadbolt said he initiated a ''round-table discussion'' on April 21 to discuss ''issues'' he had with Cr Ludlow, and nearly every councillor who spoke also raised concerns.
Following the discussion, the nine councillors present and Mr Shadbolt signed a requisition to remove Cr Ludlow from the position. Cr Lloyd Esler, who was not present at the discussion, signed the requisition the following day.
Mr Shadbolt said consultation with the affected party was not required according to the council's standing orders.
When he sought to remove former Cr Neil Boniface from the role of deputy mayor in 2009, Cr Boniface was present at the discussion and the ''backlash'' had been severe. In an attempt to avoid a similar situation he decided Cr Ludlow would not form part of the discussion.
''It has run its course. Everyone has had their say that wanted to have their say.
''Now legal options have been placed before us, it is time to step back and focus on the really positive work the council is undertaking,'' Mr Shadbolt said.
Cr Rebecca Amundsen said the decision to have a new deputy mayor would have ''positive long-term benefits for the council''.
Cr Lesley Soper said she had accepted Cr Ludlow's resignation.
''Standing orders has a process. We have followed it. There was a resignation of the deputy mayor. End of story.''
The Southland Express contacted Cr Ludlow, but because of work commitments he was unable to comment at the time of print.
-By Petrina Wright
