In September 1992, Electromotive Division of General Motors Corp. (EMD) (plaintiff) designed a planetary bearing for use in locomotives. In January 1993, EMD began testing the bearings indoors for durability and reliability. In March 1993, EMD proceeded to test the bearings outdoors, under actual use conditions, to verify durability. As part of this field testing, EMD requested permission from Union Pacific railroad (UP) to install the bearings in some of its locomotives. UP agreed, but did not execute any confidentiality agreement or other document indicating participation in the testing. EMD did not restrict UP’s use of the locomotives containing the bearings, nor did EMD require monitoring, reports, or documentation of use. After installing the bearings, EMD shipped the locomotives to UP in July 1993. On September 29, 1994, EMD filed a patent application for the bearings. EMD thereafter filed an infringement suit against Transportation Systems Division of General Electric Co. (GE) (defendant). GE moved for summary judgment, contending the patent was invalid under the on sale bar of 35 U.S.C. § 102(b). EMD cross-moved for summary judgment, contending the bar was inapplicable because the pre-critical date use of the bearings was experimental. The district court granted GE’s motion. EMD appealed.