Judicial activism violates the canon of constitutional avoidance (i.e., where a statute can fairly be interpreted so as to avoid a constitutional issue, it should be so interpreted).
Some on the left are also challenging activist judges. They were recently spurred on by the Supreme Court decision in Citizens United expanding the right of corporations to operate as persons with political free speech rights under the US Constitution. Rather than decide the Citizens United case on narrow grounds, they actively chose to broaden the case and thereby create law that gives new rights to corporations.
But lets go back in time and ask a basic question. What gives the nine appointed US Supreme Court members the right to say whether Congress's campaign finance law (McCain & Fiengold), hailed by most Americans as progress, and signed by the President, can or cannot be applied to corporations? You won't find that power of the Supreme Court written into the US Constitution.
Article III of the Constitution states:
"The judicial Power of the United States, shall be vested in one Supreme Court... and shall extend to all Cases... arising under this Constitution..."
Begs the question, what are judicial powers. But we know "judicial powers" extend to "cases" under laws established by the Congress and Executive. i.e., decide the merits of the case relative to the law. This is different than "judicial review," which is decide the merits of the law written by Congress.
The remaining powers are divided as stated in the Tenth Amendment:
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved for the States respectively, or to the people."
The power of "activist judges" isn't in the US Constitution. But, by one of the most amazing examples of circular logic, the Supreme Court gave itself the power to review the validity of laws and then use "case law," past precedent in judicial decisions, to support this power.
Where does the Supreme Court get this right to judicial activism? The Supreme Court said so in Marbury v. Madison .
Specifics of the Marbury case aside, at issue, according to Chief Justice Marshall, was whether the Congress had the power to modify the original jurisdiction of the Supreme Court. Marshall found that Congress did not have that power, and he assumed that power for the Court.
Now, Marshall's decision raises a serious question of conflict of interest. The Court is giving the Court powers by fiat. Granted, they laid out their rationale, and reasonable people could debate those merits, and even agree on them. Nevertheless, the Court giving itself powers is an unresolved issue to this day.
Alternative Solutions Are Possible
One answer is a standing set of state Constitutional Conventions. One might ask, if the Congress can't regulate itself on writing laws that are constitutional, and giving that power to the executive branch poses certain dangers to power balance, who else is left but the Supreme Court to render such decisions? The states.
The constitutional issues, including their definition, could be posed to standing state Constitutional Conventions. They deliberate, including among states, to reach a two-thirds majority outcome. The outcome can take the form of narrowing the case to avoid a constitutional issue, render a decision (interpretation of the Constitution) or amendment of the Constitution to address the question. The later would be rare, but in as much as two thirds of the states agreed, the amendment process would be well on its way from a practical perspective.
In other words, remove judicial review from the powers of the Supreme Court and let the states decide as a reflection of the people.
Clearly there would be details to work out, like how are these standing conventions convened? How do they make decisions? Even if the "Standing Convention" isn't the way to go, other alternatives surely could be crafted by people with far greater knowledge of public administration and political science. What is important is the unresolved conflict of interest in the US Supreme Court granting itself powers in Marbury v Madison.
It is helpful to consider the words of Thomas Jefferson as he pondered Judge Marshall's power grab in Marbury v. Madison :
"To consider judges as the ultimate arbiters of all constitutional questions is a very dangerous doctrine indeed, and one which would place us under the despotism of an oligarchy. Our judges are as honest as other men, and not more so. They have, with others, the same passions for party, for power, and for privilege. But their power [is] the more dangerous, as they are in office for life, and not responsible to elective control." - Thomas Jefferson, Re: Marbury v. Madison 
Wikipedia Marbury v Madison.
2. The Case Against Judicial Review, David Cobb.