How did the Morton memos define enforcement tiers and how were they interpreted by field offices?

1. What the memos formally defined as enforcement tiers

Morton’s March and June 2011 memos set out a hierarchy that placed highest priority on aliens who pose threats to national security, border security, or public safety, designating these as the agency’s “highest enforcement priorities” ^{[1] [6]}. The guidance made clear that ICE must prioritize use of enforcement personnel, detention space, and removal resources toward those categories while acknowledging resource limits and the impossibility of pursuing every administrative violation ^{[1] [7]}.

2. How prosecutorial discretion and concrete factors were prescribed

The June 17, 2011 “prosecutorial discretion” memo instructed ICE personnel to consider discretion at all stages and set out both positive and negative factors to guide individual decisions — for example, positive factors included veterans, longtime lawful residents, family ties, victims of crime, and serious health conditions — and the memo emphasized exercising discretion as early as possible to conserve resources ^{[8] [2]}. A companion memo further stated it was generally against ICE policy to initiate removal proceedings against known immediate victims or witnesses to crime absent exceptional circumstances ^{[2] [6]}.

3. Delegation, exceptions, and legal limits the memos specified

The memos explicitly left room for exceptions and made clear they did not categorically prohibit enforcement against non‑priority individuals: ICE retained authority to apprehend, detain, and remove aliens outside the three priority categories, and field directors were empowered to make judgment calls when “compelling and exceptional factors” justified deviation from the priorities ^{[9] [10]}. The guidance also delineated which ICE employees could exercise prosecutorial discretion and urged coordination with Office of Chief Counsel in mandatory‑detention cases ^{[8] [10]}.

4. How field offices interpreted and applied the memos in practice

Scholars, practitioners, and advocacy groups documented highly uneven application across field offices: some offices appear to have operationalized the priorities and expanded use of discretion, while other offices either ignored the memo’s spirit or narrowly interpreted its exceptions, leading to inconsistent outcomes for similarly situated individuals ^{[4] [3] [11]}. Legal observers warned the memo’s language left substantial room for multiple interpretations — providing “some guidance but little clarity” for the hundreds of thousands of frontline decisions ICE makes annually ^[1].

5. Political and advocacy responses that shaped field behavior

Critics on the right characterized the memos as creating de facto amnesty and argued they constrained enforcement against criminals and fugitives; advocacy groups on the left welcomed clearer priorities but called for additional guidance and mechanisms to ensure consistent implementation ^{[5] [2] [12]}. The memos were later a focal point in litigation and politics: subsequent administrations and courts treated Morton’s memos as influential but nonbinding internal guidance, and their fate and enforcement effect depended heavily on leadership priorities and local office culture ^{[11] [4]}.

Conclusion

Morton’s memos defined a three‑tier enforcement architecture and furnished detailed prosecutorial‑discretion factors and delegation rules, while preserving agency authority to act outside the tiers in specific cases ^{[1] [8] [9]}. In practice, interpretation and application varied widely across field offices — a predictable outcome given the memos’ intentional mix of prescriptive priorities and discretionary language — and that unevenness produced the political controversy and legal disputes documented by scholars, advocates, and courts ^{[4] [3] [11]}.