Ms Dugdale last week won her case against Stuart Campbell who sued for damages after the former Scottish Labour leader claimed in a newspaper column that he had sent “homophobic tweets”.
Sheriff Nigel Ross said Ms Dugdale was incorrect to imply that Mr Campbell is homophobic, but he said her article was protected under the principle of fair comment.
Campbell Deane, who represented Ms Dugdale during the case, said changes to defamation brought forward by the Scottish Law Commission (SLC) meant such cases were unlikely to proceed in future.
The Scottish Government is currently consulting on the proposals which include the introduction of a “serious harm” test.
Had the proposed legislation already been introduced, Mr Deane said the legal system would not have helped Mr Campbell “one jot”.
“Arguably he would never even have had the chance to have had his full grievance heard in court,” Mr Deane said.
“Firstly he would have faced the serious harm threshold. Under the proposed reform it is likely that the case would have been thrown out at a preliminary evidential hearing.”
Mr Deane said the abolition of fair comment and the introduction of a new defence of “honest opinion” would make it even harder for pursuers.
He said: “All Dugdale would have required to do was argue that the statement complained of was her honest opinion and have given, in general terms, some of the factors on which that opinion was based.”
The SLC’s report seeks to make sure defamation law keeps pace with challenges posed by the internet and the growth of social media.
The recommendations have been described by Lord Pentland, the judge leading the work, as the “most substantial reform of defamation in Scottish legal history”.
The Faculty of Advocates is among those opposing the introduction of the serious harm test, arguing that the measure is unnecessary in Scotland, unlike in England where it has been used to lessen the burden on the courts.
In a submission to the Scottish Government’s ongoing consultation, the Faculty said: “It could not be suggested that the Scottish courts are currently struggling to deal with either an unwelcome volume of defamation cases or cases of dubious merit.
“Accordingly, the rationale for the English threshold simply does not exist in Scotland. The introduction of an unnecessary statutory threshold is, in our view, difficult to justify.
“It may be that further evidence ought to be sought from English practitioners in respect of the operation of this provision in practice, and this may inform and assist the proper consideration of this issue.”
Publishing his written judgment last week, Sheriff Ross said: “Ms Dugdale’s article contained the necessary elements for a defence of fair comment. It was based on true facts; the statements complained about were honest; it concerned a matter of public interest, and the comments were fair.
“Her comments were fair, even though incorrect.”
Mr Campbell had been seeking damages of £25,000.