I would start by looking into the history of the supreme court and what their function is. Start with resources about US government…checks and balances…the constitution…

There are several factors that have influenced the court over the course of its history. Today the partisan nature of the court is fairly evident. The overwhelming majority of the court is conservative having been appointed by conservative Republican Presidents. Consequently those justices reflect a pro Republican, conservative bias. Their decisions are influenced by their political and religious foundations. Both Roberts and Scalia are conservative Catholics and their views on issues like abortion certainly reflect that. Politically they favor less federal government control over business and industry. Historically the court has reflected the same kinds of bias over the years. During the depression years most of the justices had been appointed by the pro business Republican administrations of the 20’s. Consequently they found several key pieces of FDR’s New Deal to be unconstitutional. That was particularly true of the NRA. FDR threatened the court by his “court packing” scheme which never materialized but certainly sent a message. He was ultimately able to appoint liberal justices like White and Frankferter and consequently the tenor of the court began to change.

The court of the 1860’s certainly reflected the fact that the Civil War was raging although they did challenge Lincoln’s actions in Ex Parte Milligan and other cases. The late 19th century was a time of strong pro expansionist attitude and the court reflected that in the Insular cases as well as a strong segregationist viewpoint in Plessy v Ferguson.

Social movements or beliefs – Civil Rights of the 50= Brown v the Board of Education, White backlash of the 60’s= the Bakke decision, the feminist movement of the 70=Roe v Wade.

Fears Korimatsu v U.S. after WW II, Miranda v Arizona(although that generated fears that the power of law enforcement was being diminished.)

Economic interests like the Schecter v New York case, Fletcher v Peck, Dred Scott v Sanford, McCulloch v Maryland.

Struggles for political power Marbury v Madison, Cherokee v Georgia.

Religious issues like the current disposition on abortion and school prayer.

All of these issues influence a courts decisions. They are but human beings and like all humans they have bias, they have causes they support and issues they oppose. Depending on what is happening in society the court is generally going to reflect one side or the other. There have been some very notable exceptions and these people are generally considered to be the great jurists of our history. People like John Marshall, Oliver Wendell Holmes and Earl Warren certainly left an imprint on American History.