Foreign nationals and permanent residents may be arrested and detained at the port of entry or after they arrive in Canada. CBSA has the authority to do such arrests. Also, a member of the Immigration Division (ID) may order the detention of an individual at an admissibility hearing following the submission of a CBSA officer.

The first detention review hearing must be conducted within 48 hours of detention followed by a 7th day review hearing and 30 day there after, until the individual is either deported or his/her situation is legally resolved.
A foreign national or a permanent resident may be found inadmissible on one of the following grounds:​​

1. Criminality
2. Serious Criminality
3. Organized Criminality
4. Health Grounds
5. Financial Reasons
6. Security Risk
7. Human or International Rights Violations
8. Misrepresentation
9. Cessation of Refugee Protection
10. Failure to Comply with the IRPA
11. Inadmissible Family Member

Usually a number of agencies are involved in identifying inadmissible foreign nationals.

Government of Canada Website Link:

1. https://www.irb-cisr.gc.ca/en/pages/index.aspx
2. https://www.canada.ca/en/immigration-refugees-citizenship/services/immigrate-canada/inadmissibility.html