What does the blue ribbon at Donald Trump's speech mean? Warren and others answer.

A number of members of Congress were spotted wearing a blue ribbon on their lapel during President Donald Trump's joint address Tuesday night.

That ribbon — the same one many Hollywood celebrities wore to Sunday night's Academy Awards — are a show of support for the American Civil Liberties Union, which is fighting back against Trump's travel ban and immigration policies.

Among the members wearing the ribbon were Sen. Elizabeth Warren (D-Mass.), who brought an Iraqi refugee who would have been caught up in Trump's travel ban as her guest.

Other members of Congress tweeted that they were also sporting the ribbon, including freshman Rep. Dwight Evans (D-Pa.) and Sen. Sheldon Whitehouse (D-R.I.).

The ACLU thanked members who wore the ribbon.

"Thank you for wearing our blue ribbon to let everyone know you #StandWithACLU Sen. Warren!" the ACLU tweeted.