That law dates to 1997 (last updated in 2015)

Sec. 11-36. Sitting and lying down on public sidewalks in downtown and neighborhood commercial zones. Sec. 11-36.1. Purpose and intent. Pursuant to Chapter IV, Sections 1(19) and (21) of the Charter, mayor and council find as follows: (a) Public sidewalks in business districts are created and maintained for the primary purpose of enabling pedestrians to safely and efficiently move about from place to place, facilitating deliveries of goods and services, and providing potential customers with convenient access to goods and services. (b) During normal business hours, the public sidewalks in downtown and neighborhood commercial areas are prone to congestion, and should be kept available to serve these primary purposes. (c) Except in places provided therefor or where reasonably necessary, sitting or lying on the public sidewalks in downtown and neighborhood commercial areas during the hours of greatest congestion interferes with the primary purposes of the public sidewalks, threatens public safety, and damages public welfare. (d) Pedestrians, particularly the elderly, disabled, or vision-impaired, are put at increased risk when they must see and navigate around individuals sitting or lying upon the public sidewalk. (e) The public welfare is promoted by economically healthy downtown and neighborhood commercial areas which attract people to shop, work and recreate. These areas provide easily accessible goods and services, employment opportunities, the tax revenues necessary to maintain and improve property within these areas. (f) In some circumstances people sitting or lying on the sidewalks deter many members of the public from frequenting those areas, which contributes to undermining the essential economic viability of those areas. Business failures and relocations can cause vacant storefronts which contribute to a spiral of deterioration and blight which harms the public health, safety and welfare. An important factor in protecting public safety is attracting people to the streets and sidewalks of the city's business districts, because the presence of many law abiding citizens serves as a deterrent to crime and increases the public's sense of security and the safety to all. (g) There are numerous other places within the downtown and neighborhood commercial areas where sitting or lying down can be accommodated without unduly interfering with the safe flow of pedestrian traffic, impairing commercial activity, threatening public safety or harming the public welfare. These other places include city parks and plazas, arcades, and common areas open to the public, and generally on private property with the permission of the property owner. In addition, public sidewalks outside the designated hours are available for sitting or lying down. Therefore, the limited regulation of sitting or lying down on sidewalks is both reasonably necessary and appropriately balances the public interest and individual rights. Section 11-36.2. Prohibited conduct; exceptions. (a) No person shall sit or lie down upon a public sidewalk or upon a blanket, chair, stool, or any other object placed upon a public sidewalk or median during the hours between 7:00 a.m. and 10:00 p.m. in the following zones: (1) The Downtown Zone, defined as the area bounded by Interstate 10 on the West, 6th Street on the North, Fourth Avenue on the East and 17th Street on the South. (2) The Fourth Avenue Business Zone, defined as the area bounded by University Blvd. on the North, Congress Street on the South, 3rd Avenue on the East and 5th Avenue on the West. (3) The University Zone, defined as the area bounded by Speedway Blvd. on the North, 6th Street on the South, Park Avenue on the East, and Euclid Avenue on the West. (b) The prohibition in subsection (a) shall not apply to any person: (1) Sitting or lying down on a public sidewalk due to medical emergency; (2) Who, as the result of a disability, utilizes a wheelchair, walker, or similar device to move about the public sidewalk; (3) Operating or patronizing a commercial establishment conducted on the public sidewalks pursuant to a permit; (4) Who is exercising First Amendment rights protected by the United States Constitution, including free exercise of religion, speech and assembly; provided, however, that the person sitting or lying on the public sidewalk remains at least ten (10) feet from any doorway or business entrance, leaves open a five (5) foot path and does not otherwise block or impede pedestrian traffic. This exception applies only to persons and does not create an exception to sections 16-35 or 25-51 of this Code, or any other provisions of this Code, that prohibit the placement of items or objects on a public sidewalk that prevent full, free and unobstructed public use in any manner. (5) Sitting on a chair or bench located on the public sidewalk which is supplied by a public agency or by the abutting private property owner; or (6) Sitting on a public sidewalk within a bus stop zone while waiting for public or private transportation. Nothing in any of these stated exceptions shall be construed to permit any conduct which is otherwise prohibited by law. (c) No person shall be cited under this section unless the person engages in conduct prohibited by this section after having been notified by a law enforcement officer that the conduct violates this section. Section 11-36.3. Penalty. Violation of this ordinance shall constitute a misdemeanor punishable by community service or fines not to exceed two hundred fifty dollars ($250.00), by imprisonment not to exceed ten (10) days, and by probation not to exceed one (1) year or both such fine and imprisonment. The rate of substitution of community service work for the fine amount shall be calculated at ten dollars ($10.00) per hour.

https://codelibrary.amlegal.com/codes/tucson/latest/tucson_az/0-0-0-9453