The Illinois Appellate Roundup, Episode 5 — DNA Experts, Sentencing Limits, and a New Post-Conviction Law

This week's Illinois Appellate Roundup follows a criminal case across three of its stages — the evidence at trial, the sentence, and the long road of post-conviction review — and adds a brand-new statute signed into law this week.

In People v. Taylor (Fourth District), the court held that the facts and data underlying a forensic expert's opinion go to the weight of that opinion, not its admissibility. A DNA analyst need not spell out her methodology on direct examination; foundation gaps are for cross-examination. The court rejected a contrary decision as an outlier and affirmed. Takeaway: attack a thin-foundation expert on cross — the court will not exclude the opinion just because the method was not detailed up front.

In People v. Boyd (Third District), the court held that after a probation revocation a defendant may be sentenced only up to the maximum he was admonished to at his plea — here, seven years, not an extended fourteen. Because the judge may have been influenced by the inflated range, it was second-prong plain error; the sentence was vacated and remanded. Takeaway: go back to the original plea admonishment — that first-stated maximum caps the exposure.

In People v. Sanchez (First District), the court held that fundamental fairness can relax res judicata and the cause-and-prejudice bar where new emerging-adult brain-science evidence supports an as-applied proportionate-penalties challenge. Sanchez, twenty at the time of the offense, made a substantial showing that his mandatory life sentence is unconstitutional as applied; the dismissal was reversed and remanded for an evidentiary hearing. Takeaway: youth-development science can reopen a successive petition — but tie it closely to your client.

And the law itself moved this week. Senate Bill 248, signed July 10, 2026, eliminates the "cause" half of the cause-and-prejudice test for successive post-conviction petitions by those who committed their offense before age twenty-one and claim their sentence violates the proportionate-penalties clause. It answers People v. Moore (2022). Prejudice must still be shown — but the cause barrier is gone.

Watch the full episode above for the plain-English holding and practical takeaway on each. This post is for general educational purposes only and is not legal advice.

Facing an appeal or a post-conviction matter in Illinois? Call David Lewarchik directly at 312-517-3877, or visit www.appealcounsel.com.