A question - could states have differing standards for what constitutes illegal trespass?
I would think that the standard would be set by what constitutes an illegal alien.
Congress sets the uniform rules of naturalization, so states would have to abide by the rules that establish lawful from unlawful entry.
I would focus on the international border states first and not worry about interior states. From Title 8-ALIENS AND NATIONALITY CHAPTER 12-IMMIGRATION AND NATIONALITY SUBCHAPTER II-IMMIGRATION Part VIII-General Penalty Provisions §1325. Improper entry by alien. it says:
In Texas, it should be easy to have the Texas Rangers patrol the border area and pick up people who are crossing away from designated entry checkpoints. These people are certainly trespassing.§1325. Improper entry by alien
(a) Improper time or place; avoidance of examination or inspection; misrepresentation and concealment of facts
Any alien who (1) enters or attempts to enter the United States at any time or place other than as designated by immigration officers, or (2) eludes examination or inspection by immigration officers, or (3) attempts to enter or obtains entry to the United States by a willfully false or misleading representation or the willful concealment of a material fact, shall, for the first commission of any such offense, be fined under title 18 or imprisoned not more than 6 months, or both, and, for a subsequent commission of any such offense, be fined under title 18, or imprisoned not more than 2 years, or both.
(b) Improper time or place; civil penalties
Any alien who is apprehended while entering (or attempting to enter) the United States at a time or place other than as designated by immigration officers shall be subject to a civil penalty of-
(1) at least $50 and not more than $250 for each such entry (or attempted entry); or
(2) twice the amount specified in paragraph (1) in the case of an alien who has been previously subject to a civil penalty under this subsection.
Civil penalties under this subsection are in addition to, and not in lieu of, any criminal or other civil penalties that may be imposed.
(c) Marriage fraud
Any individual who knowingly enters into a marriage for the purpose of evading any provision of the immigration laws shall be imprisoned for not more than 5 years, or fined not more than $250,000, or both.
(d) Immigration-related entrepreneurship fraud
Any individual who knowingly establishes a commercial enterprise for the purpose of evading any provision of the immigration laws shall be imprisoned for not more than 5 years, fined in accordance with title 18, or both.
§1225. Inspection by immigration officers; expedited removal of inadmissible arriving aliens; referral for hearing
(a) Inspection
(1) Aliens treated as applicants for admission
An alien present in the United States who has not been admitted or who arrives in the United States (whether or not at a designated port of arrival and including an alien who is brought to the United States after having been interdicted in international or United States waters) shall be deemed for purposes of this chapter an applicant for admission.
So even someone who was captured in the middle of the west Texas desert and brought to Immigration Control will be considered an applicant for admission as if they had crossed the proper entry point. The difference is that they won't have the valid entry papers (valid passport and visa).
§1225 and §1325 seem to be at odds with each other, as §1225 says to treat them as an applicant for admission but §1325 says they can be imprisoned for up to six months.
Therefore, I think it will take a court challenge to weed out the inconsistent language that seems to have been patchwork applied to prior law.
At the minimum, a "trespasser" should be anyone observed by state law enforcement to be crossing the border away from designated points of entry and without out any required documents for entry.
Keep in mind that this is all top-of-mind since reading how much the US Code has changed since the last time I looked at it.
-PJ