SparkNet has been protective of its format, unsuccessfully filing trademark infringement suits against Bonneville International for its use of the Jack FM service-marked slogan "Playing What We Want" and other similar phrases.

[3] For this reason, many stations airing a Jack-like format use slightly different slogans to avoid infringing on SparkNet's service marks: WBEN-FM in Philadelphia uses the tagline "Playing anything we feel like."

[citation needed] In place of DJs, the Jack character makes sarcastic or ironic remarks and quips, often using self-deprecating humor.

Each September, all Jack FM stations ask listeners to visit a certain link to evaluate which songs should be played on the radio and which ones should be swapped.

Rogers Communications claims that the only thing taken without permission, for the Jack FM radio station, in Vancouver, British Columbia, Canada, was the name and the tagline.

Program director Howard Kroeger was inspired to create Bob FM after hearing a mixtape at a friend's 40th birthday party.

The success of Jack caused a cloning effect, with some stations using the names of famous local figures, landmarks, or symbols to promote their version of the format.

On July 29, 2005, Rawlco's CKCK-FM in Regina, Saskatchewan, became the first non-Rogers station in Canada to directly license the Jack FM brand rather than adopting an alternate name.

Listeners and staffers alike were surprised by the sudden change because many of the station's long-time air personalities were considered Baltimore institutions.

The switch to the format, with no DJs and few songs before 1980 was termed The Day the Music Died by some New Yorkers and has drawn criticism even from non-listeners of the station.

[8] The sudden firing of DJs of historic renown such as Cousin Brucie, Ron Lundy and Harry Harrison was noted in the press.

According to the New York Post, mayor Michael Bloomberg responded to the change by declaring he would "never listen to that fucking CBS radio ever again" (the quote was censored in the newspaper).

[9] Three of the fired DJs and staff (Dan Taylor, Bob Shannon, and Mr. G) returned to the station, along with newsman Al Meredith (who had stayed at the station during Jack FM doing his Sunday morning public affairs show), as well as DJ Pat St. John who had previously left CBS-FM for Q104.3 about a year before the flip to Jack.

In November 2005, Cardinal defended his decision in an interview with Michael Hainsworth of Report on Business Television and stated why he doesn't see commercial-free iPods and satellite radio as a threat to a non-DJ format.

[10] In October 2005, Entravision Radio launched a Spanish-language version of the Jack format dubbed "José" with the "We Play What We Want" tagline translated into Spanish as "Toca lo que Quiere".

However, in many cities the novelty wore off, and in the late 2000s a number of Jack stations modified their playlists drastically or flipped to other formats outright.

[14] Two further Jack FM stations were planned on DAB digital radio from 2008 for Northamptonshire and Northeast Wales and West Cheshire[citation needed] but by August 2009 were a year late with no indication of an ETA.

[15] In January 2007, KAJR in California's Coachella Valley launched as a "Jack FM" affiliate in a region unable to receive the KCBS-FM signal from Los Angeles, 100 miles (160 km) to the west.

[17] This move by program director Mike O'Reilly drew the ire of fans who live outside the city limits, including the large U.S. military community stationed locally and overseas.

O'Reilly explained his rationale, citing a new Arbitron policy on how online listening is measured: Our radio industry is continually adapting to changing metrics, which are sometimes out of our control within our competitive landscape.

I understand your frustration and I can assure you this decision to restrict our streaming efforts to San Diego was based on multiple factors including the licensing issues outlined on our website.

Meanwhile, in February 2015, another Rogers station, CHTT-FM in Victoria, British Columbia, dropped the Jack FM format and flipped to contemporary hit radio (CHR) as "Kiss 103.1".

[19] US military radio station Armed Forces Network, Afghanistan broadcasts Jack FM, having adopted the format on August 1, 2011, as a way to expand the playlist and reduce operational personnel.

[22] OXIS Media, who manage the brand, was set up by Clive Dickens, Ian Walker, Donnach O’Driscoll and Adrian Robinson, who had been involved with establishing Virgin Radio[23] (now Absolute).