The correct answer to this open question is the following.
Unfortunately, you did not attach the text or excerpt for reference. So we do not know what word is represented by the question mark.
However, trying to help you we can comment on the following general terms.
The fear that could justify a state's right to limit an individual's constitutional rights is "subversion" or during war times.
During those above-mentioned scenarios, the government could think to limit constitutional rights in order to protect the security of the nation, including the people.
Something similar has happened during World War I and World II, times in which the government tried to limit free speech to suppress critics and to control ane espionage activities that could cause treason.