Please help me out with at least three points for the following debate topic: the government should limit civil liberties during a national crisis.

As Pushaw (2009; see the source below) notes, American Presidents' restrictions on civil liberties during war time or other times of national crisis did not lead to a complete revocation of those rights. In fact, these limits often led to greater rights or to making up the infringements on civil liberties later. For example, during the Civil War, President Lincoln revoked civil liberties in some border states. However, after the war, the 13th, 14th, and 15th Amendments were passed, ending slavery, granting African-American people citizenship, and granting all men the right to vote, respectively. In other words, one reason to revoke civil rights during times of crisis is to create or protect civil rights after the crisis has passed. It has been documented, according to Pushaw (2009) and other scholars, that a time in which civil liberties are revoked is usually followed by a period of greater civil liberties when leaders try to make up for the temporary infringement on civil liberties. 
In addition, Article I of the Constitution gives the government the right to revoke the writ of habeas corpus "when in Cases of Rebellion or Invasion the public Safety may require it.” In addition, in the case Schenck v. United States (1919), the Supreme Court ruled that Schenck's right to free speech (he mailed letters to draftees in World War I, telling them the draft was wrong) was not protected. The court ruled that speech that creates "a clear and present danger" can be prohibited, and the right to free speech that is protected in peace time is not always protected in wartime. Therefore, there is legal precedent and a constitutional right for the government to rescind civil liberties during national crises, such as wars. 
Finally, many of the enemies that pose a threat to the United States and other Western countries today do not come from large, organized entities such as countries. Instead, terrorists come from loosely organized groups, and they are not identifiable by uniforms or by association with organized armies. They use tactics that do not respect the rule of law. Therefore, in order to combat and contain these types of forces, some people argue that government cannot use traditional methods; instead, the government must use methods such as military tribunals and other means to hold these suspected or known combatants to keep our country safe. 
Source:
Pushaw, Robert J., Jr. (2009). "Justifying Wartime Limits on Civil Rights." Chapman Law Review Spring 2009 Symposium Issue. http://www.chapmanlawreview.com/archives/1556
https://www.oyez.org/cases/1900-1940/249us47