In United City of Yorkville v. Village of Sugar Grove, 376 Ill. App. 3d 9, 875 N.E.2d 1183, 314 Ill. Dec. 896 (2007), the court dealt with the effect of an amendment on a boundary dispute between two municipalities. The municipalities had entered into boundary agreements, later determined to conflict with each other. After the agreements were entered into, the Illinois Municipal Code was amended to provide that a conflict rendered the first agreement unenforceable. The trial court held that the amendment did not apply retroactively. The appellate court agreed, explaining as follows: "Yorkville takes the position that the amendment to section 11-12-9 is procedural because '[i]t directly relates to a method of enforcing boundary line agreements authorized under section 11-12-9 and prescribes a method of enforcing rights and obtaining redress when two boundary line agreements conflict.' (Emphasis added.) We reject that position. In fact, the statute is silent as to the pleading, evidence and practice for establishing the unenforceability of allegedly conflicting agreements. The amendment is better characterized as creating a substantive right for a corporate authority to invalidate a prior boundary line agreement that conflicts with a more recent boundary line agreement to which the complaining authority is a party." United City of Yorkville, 376 Ill. App. 3d at 21.