After shutting down a Bernie Sanders speech at a Seattle rally for Social Security, Medicare, and Medicaid, Black Lives Matter activist Marissa Johnson declared to MSNBC’s Tamron Hall that she was motivated by a desire to hold liberal candidates accountable.

This is more than understandable. Despite boosting progressives’ expectations, President Obama has continued to prosecute a shadowy global “war on terror,” undermined public education by promoting charter schools, and reneged on promises to organized labor for the Employee Free Choice Act (EFCA) and to the American public for a truly universal health care system.

All this has certainly made clear the importance of holding putative liberals to their rhetoric, even for someone as young as Johnson, whose progressive political awakening only dates back to Trayvon Martin’s murder in 2012 at the hands of sociopathic vigilante George Zimmerman.