As a patrol officer working the field for a small municipal police department in Ohio, Officer Mark A. Brooks often encountered situations in the field that defied clear-cut legal answers. Gray areas often emerged that were out of the purview of his standard operating procedures.

He could legally scan license plates of vehicles in motion, but what about a car or truck parked in a private driveway or in a strip mall? And if the niece of a city official told him her relative possessed child pornography on a computer, could the subject expect privacy?

To give himself a reliable legal resource, Officer Brooks began maintaining a binder of case law as an easy reference guide for himself, fellow officers, or even less-than-fully-informed supervisors who gave him instructions that resulted in courtroom dismissals of his cases.

"I got tired of FTOs or supervisors advising me that certain powers were within my scope and when I executed those powers, I didn't know what case law granted me the authority to do so when asked by the prosecutor," says Brooks. "There have been countless times that prosecutors didn't know the case law relevant to my justification for a stop or search."

Officer Brooks eventually took his binder into the digital realm, by learning software development for the Android smartphone platform. He first produced the Ohio Cop "app" as a reference for case law in his own state. And because so many other officers responded favorably to his app, he later created U.S. Cop to bring resources to field officers outside of his own state. U.S. Cop is now one of the more widely used law enforcement apps.

Including Brooks' app, POLICE Magazine has identified 10 smartphone apps that provide potent tools for patrol officers. These 10 law enforcement apps should keep you engaged in your investigations and may just save you a trip back to the station.

We also surveyed POLICE readers to find out which apps you're using that help make your job more efficient. We've picked apps from the two most popular platforms—Apple's iOS and Android operating system—and provided details below. We've also included feedback from officers on several of the apps. We've elected not to print the names of respondents, only their agency and role.

After you read our picks for top apps, please e-mail us with your own choices at editor@policemag.com. Tell us about your favorite app, and what you like about it.

Top 5 Apple Apps for Law Enforcement

Police Partner : Clickz Designs' app enables officers to input field notes to take away the need for clunky notebooks. The interface is easy to navigate and provides fields to fill in such as witnesses, vehicles, suspects, case numbers, and other information you'd expect to be included in a police report. Seek legal guidance before using this one, as your notes may be considered exculpatory evidence and subject to discovery by a defense attorney. Cost: $1.99.

Spanish for Police : Exact Magic Software's app provides Spanish commands and questions organized in basic law enforcement categories such as Officer Safety, Arrests; Searching Suspects; Miranda Warning; DUI/HGN and others. Phrases in the Officer Safety category include "Hands out of pockets," "Do not resist," and "Drop it." Cost: $2.99.

MobileArms for Glock: MobileArms' Glock Edition app provides details of every Glock model, search by model or caliber, photos, company history, and a list of gun dealers and shooting ranges for every state. It also includes quick-schematics, including field and armor. Cost: $1.99.[PAGEBREAK]

Offender Locator: Offender Locator by ThinAir Wireless provides locational data from registered offender databases in all 50 states. The app's GPS function allows officers to search for offenders via address, current location, offender name, or a name in your iPhone contacts. Offenders are listed or mapped (red pin icons), and a detail screen provides basic info and offenses. For an Austin (Texas) PD patrol officer, the app "lets me know up-front who I'm dealing with, and if subject is in compliance." Cost: 99 cents.

N-Number: Digital IQ's N-Number app allows officers to get detailed information on aircraft via the "N" or tail number required by the FAA for registration of civil aircraft. The app categorizes the data on three screens-Aircraft, Engine, and Owner. The Aircraft screen provides a detail screen giving the manufacturer, model, type, year, serial number, and number of seats. Investigators can get the address where the aircraft is registered, among other data.

Top 5 Android Apps for Law Enforcement

Droid Law : BigTwit Software's DroidLaw 2.0 allows officers to search sections of state criminal (penal) codes on their mobile devices. This saves valuable time, so officers don't have to pull out the "old code book" and search for the right law or keyword. The app is a shell, and individual states must be downloaded. DroidLaw also provides U.S. copyright law (Title 17), U.S. patent law (Title 35), the U.S. Code, U.S. Supreme Court cases through 2010, and the U.S. Constitution. The app provides one Hamilton County (Ind.) Sheriff's Office deputy a "quick in-hand reference of statutes." Cost: Free.

Smart Tools : For those of you who enjoy the finer points of forensics, Android Boy's Smart Tools is for you. It provides tools for length and angle, distance and height, sound and vibration, as well as a compass and metal detector. The app uses the camera for some of the tools (height, distance, and compass) to provide an accurate reading of the scene you're viewing. The maximum distance measurement on a Motorola Droid 2 is about 300 feet. Cost: $1.99.

U.S. Cop : Mark Brooks' app is organized into tabs such as Index, Case Law, Training, and Messages. The Index section, for example, includes a Traffic section with subsections for information concerning states that require front license plates, accident investigation helps, traffic-stop case law, a tire's size-speed difference, window tint laws, CMV (Commercial Moving Vehicle) out-of-service orders, CMV company snapshots, and LIDAR instructions. The DUI section provides information and instructions on Standardized Field Sobriety Tests (SFST). Officers who answered the survey generally credited the app for providing excellent reference material that's easy to access; many officers said the app helps them identify pills they recover from subjects. Cost: $1.99.

Police Pad : This app from nattayb is a field-reporting tool allowing users to create an "event" with time and date recorded. Events are categorized into tabs such as New Call, On Scene, Interview, Arrest, Ticket, Statement, Car Accident, and Booked. Supporting information such as pictures, voice notes, and text can be added. As with Police Partner, seek legal advice before using this one. Cost: $1.99.

Cargo Decoder: Strategies In Software's app provides first responders a guide to the material stored in trucks or tankers. A Voice Search feature allows fast querying, and partial UN/NA numbers or material names are recognized. The app provides information on toxic inhalation hazards and protective distance. Cost: Free.

Related:

Smartphone Apps for Cops

Is There An App for That?

Smartphone Apps for LE (photos)