Automatic Deportation order is defined under Section 32 of the UK Border Act 2007.
Automatic deportation
(1) In this section “foreign criminal” means a person—

(a) If a person is not a British citizen,
(b) Who is convicted in the United Kingdom of an offence, and
(c) To whom Condition 1 or 2 applies.

(2) Condition 1 is that the person is sentenced to a period of imprisonment of at least 12 months.

(3) Condition 2 is that—
(a) The offence is specified by order of the Secretary of State under section 72(4)(a) of the Nationality, Immigration and Asylum Act 2002 (c. 41) (serious criminal), and
(b) the person is sentenced to a period of imprisonment.

(4)For the purpose of section 3(5)(a) of the Immigration Act 1971 (c. 77), the deportation of a foreign criminal is conducive to the public good.

(5)The Secretary of State must make a deportation order in respect of a foreign criminal (subject to section 33).

(6)The Secretary of State may not revoke a deportation order made in accordance with subsection (5) unless—
(a) he thinks that an exception under section 33 applies,
(b)the application for revocation is made while the foreign criminal is outside the United Kingdom, or
(c) section 34(4) applies.

(7)Subsection (5) does not create a private right of action in respect of consequences of non-compliance by the Secretary of State.

However there are certain exceptions such as:
a) Exemption 1 is where removal of a foreign national criminal in pursuance of the deportation order would breach-

1) A person’s convention rights
2) The United Kingdom Obligations under the Refugee Convention
3) Breach of Article 8 of Human Rights, parent of a British Child and a child contact order in place.