http://www.americanthinker.com/2010/05/what_exactly_is_social_justice.html "Social justice" is intended to remedy this exploitation of workers by capitalists. Marx saw man only in a social context -- meaning not as an individual, but as a part of a class. Thus, the word "social" (in "social justice") refers to classes in a society.
"Justice," in the Marxist context, means economic equality. This is the Marxist utopian ideal that all members in a society should receive the same amount of compensation, regardless of occupation, skill, or work ethic. The oft-quoted socialist mantra, "From each according to his ability, to each according to his need," comes from this concept.
Social justice can be accomplished in only one way in a capitalist society -- by wealth redistribution. This is done by seizing the wealth of the greedy rich and giving it to the poor, using the government as the agent of redistribution. This is the true aim of the left's social justice agenda.
Marx's dim view of capitalism must be put in context, taking into consideration the time and place in which he lived. In 1848, the year of The Communist Manifesto's publication, the Industrial Revolution was at its height in Europe. In many European towns, the skies were filled with black smoke spewing from massive factories that employed scores of workers in horrible conditions.
However, just as Marx's understanding of capitalism was limited to factories existing in 1840s Europe, his criticisms of capitalism must be likewise limited. Marx's philosophy is demonstrably false in the modern-day United States.
To begin with, Marx contemplated only two classes. One was a very small and privileged class of property and business owners; the remainder of the population was grouped into a massive class of impoverished workers. Therefore, Marxism cannot account for the millions of American middle-class property owners, nor can it explain the existence of small businesses, which are the backbone of the American economy.
People who enjoy their job or make more than a subsistence wage are also inexplicable under Marxism, as are "rags to riches" stories and anyone advancing in salary or position. Those people simply don't exist in the Marxist world.