AUT University in Auckland was given permission last year to offer a bachelor of laws degree from this year.
It has a commercial law focus and has attracted about 90 students.
It is the first new law course since Waikato University introduced a programme in 1990.
There are also courses at Victoria University in Wellington, the University of Auckland and the University of Canterbury.
The AUT course "had made no difference" to enrolments at Otago, law faculty dean Prof Mark Henaghan said.
About 640 students had enrolled in first-year law intermediate papers this year, about the same number as past years, and all 220 places in second-year classes were filled.
As usual, Otago University had received more than 600 applications for second-year places this year.
Prof Henaghan said he was confident Otago would maintain numbers.
"I think if students are going to come to Otago, they will come to Otago.
"Waikato might be the university affected in years to come as some of their students are from Auckland."
Until now, there has been only one law school in Auckland, at the University of Auckland.
Typically, more than 1000 students apply for about 300 second-year places.
Asked if there was still room for another law school to meet demand, Prof Henaghan said he did not think so.
Universities had to balance increasing the number of students while ensuring resources were not stretched, and teaching effectiveness and course quality were maintained, he said.
For those reasons, Otago continued to keep its number of second-year places to about 220.
