U.S. District Court Judge Gonzalo Curiel of the Southern District of California issued the ruling, Reuters reported.
Apple sued Qualcomm two years ago, claiming the chipmaker had violated the terms of a cooperation agreement between the two companies, according to the report.
The ruling won't take effect until after a trial in the case is completed, according to the report.
Qualcom shares fell 20 cents in after-hours action to $55.20. Apple rose 32 cents to 184.05.
Apple is expected to report on May 7 earnings of $2.40 a share on sales of $57.6 billion in the current quarter, based on a FactSet survey of 36 analysts. In the same period a year ago the electronic devices maker and services provider posted earnings of $2.73 a share on sales of $61.1 billion.
The stock has risen 17.5% since the company last reported earnings on Jan. 29. Quarterly estimates have fallen less than 1 cent a share in the past month. Apple is currently trading at a price-to-forward-earnings ratio of 15.2 based on the 12-month estimates of 42 analysts surveyed by FactSet.
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Qualcomm is expected to report April 24 earnings of 70 cents a share on sales of $4.8 billion for the current quarter, based on a FactSet survey of 19 analysts. In the same period a year ago the company posted earnings of 80 cents a share on sales of $5.2 billion.
The stock has risen 10.4% since the company last reported earnings on Jan. 30. Qualcomm is currently trading at a price-to-forward-earnings ratio of 13.3 based on the 12-month estimates of 21 analysts surveyed by FactSet.
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