Judicial activism is intrinsic. Judges continually encounter situations not straightforwardly covered in any laws. They have to drag the laws onto the new situations, and extend the laws’ original sense. Through the system of precedent, the ad hoc extensions become law. Eventually, many laws end up covering areas alien to the lawmakers’ intent.
Additionally, many judges, especially of Supreme Courts, find professional indulgence in scholastic exercises. They seek hidden meaning in laws, or rather find ways to inject a predetermined meaning into the laws. Hard to believe but true nonetheless, many judges have a sadistic urge to “let Rome fail but the law triumph.” They subconsciously trample on commonsense values with wild legal interpretations. For them, this is a way of placing themselves above society and its wants and needs.
In many cases, though, the judges can be beaten with their own weapon, legalese. Thus, in 2000 the Supreme Court ruled that no community in Israel can refuse admittance to Arabs. Besides the direct security risk Arabs pose to Jewish residents, it’s just abominable to have them around. But it remains legal to exclude people of other religions. Jews can form religious neighborhoods and refuse residence to those who don’t practice Judaism; that would rid the townships of Muslims.