You might want to have the New American Bible sourced, that's our defacto bible, although it's not always as flowery and scholars don't really use it, it contains what we believe.
It could give you a concise answer without me elaborating.
But now the righteousness of God has been manifested apart from the law, though testified to by the law and the prophets, the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction; all have sinned and are deprived of the glory of God.
(Romans 3:21-22)
For we consider that a person is justified by faith apart from works of the law.
(Romans 3:28)
http://www.usccb.org/bible/romans/romans3.htm
A worker’s wage is credited not as a gift, but as something due. But when one does not work, yet believes in the one who justifies the ungodly, his faith is credited as righteousness. So also David declares the blessedness of the person to whom God credits righteousness apart from works:
(Romans 4:4-6)
http://www.usccb.org/bible/romans/romans4.htm
The people Paul was admonishing were those who those who felt justified by works of the law, he's echoing Jesus's lament about the Pharisees who felt that washing their hands was more important than taking care of their parents.
I believe there is a distinction, and correct me if I'm wrong, but Protestant bibles don't mention works of the law just works right? I think that's one of the fundamental differences between our confessions.