according to the constitution, a writ of habeas corpus may not be suspended except under what conditions?

According to the U.S. Constitution, the writ of habeas corpus may not be suspended except “in cases of rebellion or invasion when the public safety may require it.”

In other words, two conditions must both be present:

• There is a rebellion or invasion threatening the country.

• Suspending the writ is reasonably judged necessary for public safety in that emergency.

This language comes from Article I, Section 9, Clause 2 of the Constitution, often called the Suspension Clause.

TL;DR: It can only be suspended during a rebellion or invasion, and only when public safety requires it.