Under most US and Canadian law, a person may be found guilty of some form of mischief when that person intentionally participates in the destruction of an abandoned building.
In the United States, this charge is of the fourth degree, and thus a misdemeanor.
In Canada, however, it is an indictable offence, and depending on the nature of it, the charges range from a summary conviction (ticket) to life imprisonment. If your destruction of property constitutes, in the following approximate priority:
Endangerment to life (you make a deathtrap), life in prison.
Damage to a place or object of worship, with the intent to commit a hate crime, 18 months (summary) to 2 years.
Damage to something worth more than $5000, cultural property, or data (records), a ticket to 10 years.
Damage to anything else, a ticket to 2 years.
The prosecution generally must be able to demonstrate that the Urban Explorer willfully intended to vandalize some property, or in the US, an abandoned building. In your defence, you should show evidence of your 'hobby' and your ethics "Take only pictures, leave only footprints."
Sadly, having a sweet portfolio and a best-selling coffee-table book may not be enough credibility. The offense varies upon the state (and obviously by country) and there really is no uniformity. There are a few items that are just about universal. * Usually, if the property is posted, the grading of the offense usually rises (find a plausible entry-point that is devoid of signs). In Canada, this has nothing to do with mischief, but will make trespassing more severe. * Barriers (doors, fences, barricades, motes, windows)(In British Columbia and other provinces rivers, shrubs, and other natural elements can legally be called fencing for prosecuting a trespassing charge) bypassed in many states is evidence that you are intentionally trespassing. It may also be called break and enter, and in any case will make trespassing worse for you under Canadian law. * Usually, if there is evidence that the building is being used or occupied, the severity of the offence increases. In Canada, if it is a "dwelling-place," you will usually go to jail. * In American states that have "castle doctrine" (FL, TX, VA - and more) the owner/occupier may shoot and kill you for trespassing on private land/property. In Canada, the property owner is generally justified in using "as much force as necessary" to remove you, and if you resist, it is an unprovoked assault on the owner.
It is also important to note that they can always charge you with trespassing instead, or as well.
As far as the mechanics, Most state laws specify and name an act that is forbidden: eg spitting on the sidewalk. The law then describes "elements of the offense" - meaning things you must do to be in violation. Common to all criminal violations is that it matters not if the act was committed "Knowingly, Recklessly, Intentionally, or Negligibly" you still did it, you have still committed a crime, and the police are completely with their rights to arrest you. Note the extract below from California law. There is a section dedicated strictly to INDUSTRIAL locations.
552. This article does not apply to any entry in the course of duty of any peace or police officer or other duly authorized public officer, nor does it apply to the lawful use of an established and existing right of way for public road purposes.
552.1. This article does not prohibit: (a) Any lawful activity for the purpose of engaging in any organizational effort on behalf of any labor union, agent, or member thereof, or of any employee group, or any member thereof, employed or formerly employed in any place of business or manufacturing establishment described in this article, or for the purpose of carrying on the lawful activities of labor unions, or members thereof. (b) Any lawful activity for the purpose of investigation of the safety of working conditions on posted property by a representative of a labor union or other employee group who has upon his person written evidence of due authorization by his labor union or employee group to make such investigation.
553. The following definitions apply to this article only: (a) "Sign" means a sign not less than one (1) square foot in area and upon which in letters not less than two inches in height appear the words "trespassing-loitering forbidden by law," or words describing the use of the property followed by the words "no trespassing." (b) "Posted property" means any property specified in Section 554 which is posted in a manner provided in Section 554.1. (c) "Posted boundary" means a line running from sign to sign and such line need not conform to the legal boundary or legal description of any lot, parcel, or acreage of land, but only the area within the posted boundary shall constitute posted property, except as otherwise provided in subdivision (e) of Section 554. 1.
554. Any property, except that portion of such property to which the general public is accorded access, may be posted against trespassing and loitering in the manner provided in Section 554.1, and thereby become posted property subject to the provisions of this article applicable to posted property, if such property consists of, or is used, or is designed to be used, for any one or more of the following: (a) An oil well, oilfield, tank farm, refinery, compressor plant, absorption plant, bulk plant, marine terminal, pipeline, pipeline pumping station, or reservoir, or any other plant, structure, or works, used for the production, extraction, treatment, handling, storage, or transportation, of oil, gas, gasoline, petroleum, or any product or products thereof. (b) A gas plant, gas storage station, gas meter, gas valve, or regulator station, gas odorant station, gas pipeline, or appurtenances, or any other property used in the transmission or distribution of gas. (c) A reservoir, dam, generating plant, receiving station, distributing station, transformer, transmission line, or any appurtenances, used for the storage of water for the generation of hydroelectric power, or for the generation of electricity by water or steam or by any other apparatus or method suitable for the generation of electricity, or for the handling, transmission, reception, or distribution of electric energy. (d) Plant, structures or facilities used for or in connection with the rendering of telephone or telegraph service or for radio or television broadcasting. (e) A water well, dam, reservoir, pumping plant, aqueduct, canal, tunnel, siphon, conduit, or any other structure, facility, or conductor for producing, storing, diverting, conserving, treating, or conveying water. (f) The production, storage, or manufacture of munitions, dynamite, black blasting powder, gunpowder, or other explosives. (g) A railroad right-of-way, railroad bridge, railroad tunnel, railroad shop, railroad yard, or other railroad facility. (h) A plant and facility for the collection, pumping, transmission, treatment, outfall, and disposal of sanitary sewerage or storm and waste water, including a water pollution or quality control facility. (i) A quarry used for the purpose of extracting surface or subsurface material or where explosives are stored or used for that purpose.
554.1. Any property described in Section 554 may be posted against trespassing and loitering in the following manner: (a) If it is not enclosed within a fence and if it is of an area not exceeding one (1) acre and has no lineal dimension exceeding one (1) mile, by posting signs at each corner of the area and at each entrance. (b) If it is not enclosed within a fence, and if it is of an area exceeding one (1) acre, or contains any lineal dimension exceeding one (1) mile, by posting signs along or near the exterior boundaries of the area at intervals of not more than 600 feet, and also at each corner, and, if such property has a definite entrance or entrances, at each such entrance. (c) If it is enclosed within a fence and if it is of an area not exceeding one (1) acre, and has no lineal dimension exceeding one (1) mile, by posting signs at each corner of such fence and at each entrance. (d) If it is enclosed within a fence and if it is of an area exceeding one (1) acre, or has any lineal dimension exceeding one (1) mile, by posting signs on, or along the line of, such fence at intervals of not more than 600 feet, and also at each corner and at each entrance. (e) If it consists of poles or towers or appurtenant structures for the suspension of wires or other conductors for conveying electricity or telegraphic or telephonic messages or of towers or derricks for the production of oil or gas, by affixing a sign upon one or more sides of such poles, towers, or derricks, but such posting shall render only the pole, tower, derrick, or appurtenant structure posted property.
555. It is unlawful to enter or remain upon any posted property without the written permission of the owner, tenant, or occupant in legal possession or control thereof. Every person who enters or remains upon posted property without such written permission is guilty of a separate offense for each day during any portion of which he enters or remains upon such posted property.
555.1. It is unlawful, without authority, to tear down, deface or destroy any sign posted pursuant to this article.
555.2. It is unlawful to loiter in the immediate vicinity of any posted property. This section does not prohibit picketing in such immediate vicinity or any lawful activity by which the public is informed of the existence of an alleged labor dispute.
555.3. Violation of any of the provisions of this article is a misdemeanor.
555.4. The provisions of this article are applicable throughout the State in all counties and municipalities and no local authority shall enact or enforce any ordinance in conflict with such provisions.
555.5. If any provision of this article, or the application thereof to any person or circumstance, is held to be invalid, the remainder of the article, and the application of such provision to other persons or circumstances, shall not be affected thereby. If any section, subsection, sentence, clause, or phrase of this article is for any reason held to be unconstitutional or invalid, such decision shall not affect the validity or constitutionality of the remaining portions of this article. The Legislature hereby declares that it would have passed this article and each section, subsection, sentence, clause, or phrase thereof, irrespective of the fact that one or more of the sections, subsections, sentences, clauses, or phrases thereof be declared unconstitutional or invalid.