My memory has faded me, but I'm pretty sure that the doctrine of precedent is one aspect that could be used to evaluate the courts as law-makers.
An advantage of courts as lawmakers - is that they have the doctrine of precedent at their disposal - judges can make relevant practical decisions to the cases before them and hence form precedents that can be easily developed, referred to and built upon in future decisions because of the doctrine's flexibility.
A disadvantage of courts making law is that the use of precedent to make law causes an unorganised, unstructured development of that area of law - due to the need for a particular case to come before the court before the court can decide on a new principle of law;
Also, precedents are not necessarily 'binding' - they may be avoided by judges (reversed, overturned, disapproved, distinguished - RODD) - hence why legislating through parliament is advantageous (ie. laws may only be amended after the amendment has been voted through the House of Reps and the Senate just like a normal bill would be).