Fianna Fail's Niall Collins said he will not comment on a letter he wrote on behalf of a drug dealer until the man's sentence is finalised.
The man had pleaded guilty to possession of cannabis worth almost €18,000 for sale or supply.
At Limerick Circuit Criminal Court this week, a defence barrister said the case belonged in the "exceptional category" because of the man's family circumstances, and this was supported by a letter written by Deputy Niall Collins.
The accused is a widowed father-of-four, and is the only provider for his children after his wide died earlier this year. Mr Collins' hand-written letter appealed for leniency.
The prosecution asked that the judge attach no weight to the letter from a public representative. They said such letters were once common practice, but had thankfully stopped.
The man is due for sentencing in October.
Deputy Collins earlier told the Irish Daily Mail that any correspondence he enters into is private and is covered by data protection regulations.